For #10163 - Adds tab multiselect mode

app/src/main/java/org/mozilla/fenix/browser/BaseBrowserFragment.kt

@@ -107,7 +107,6 @@ import org.mozilla.fenix.ext.requireComponents
 import org.mozilla.fenix.ext.sessionsOfType
 import org.mozilla.fenix.ext.settings
 import org.mozilla.fenix.home.SharedViewModel
-import org.mozilla.fenix.tabtray.TabTrayDialogFragment
 import org.mozilla.fenix.theme.ThemeManager
 import org.mozilla.fenix.utils.allowUndo
 import org.mozilla.fenix.wifi.SitePermissionsWifiIntegration
@@ -231,7 +230,10 @@ abstract class BaseBrowserFragment : Fragment(), UserInteractionHandler, Session
                 tabCollectionStorage = requireComponents.core.tabCollectionStorage,
                 topSiteStorage = requireComponents.core.topSiteStorage,
                 onTabCounterClicked = {
-                    TabTrayDialogFragment.show(parentFragmentManager)
+                    findNavController().nav(
+                        R.id.browserFragment,
+                        BrowserFragmentDirections.actionGlobalTabTrayDialogFragment()
+                    )
                 },
                 onCloseTab = {
                     val snapshot = sessionManager.createSessionSnapshot(it)

app/src/main/java/org/mozilla/fenix/collections/CollectionCreationController.kt

@@ -15,6 +15,8 @@ import mozilla.components.feature.tab.collections.TabCollection
 import org.mozilla.fenix.components.TabCollectionStorage
 import org.mozilla.fenix.components.metrics.Event
 import org.mozilla.fenix.components.metrics.MetricController
+import org.mozilla.fenix.ext.getDefaultCollectionNumber
+import org.mozilla.fenix.ext.normalSessionSize
 import org.mozilla.fenix.home.Tab
 
 interface CollectionCreationController {
@@ -92,7 +94,7 @@ class DefaultCollectionCreationController(
         }
 
         metrics.track(
-            Event.CollectionSaved(normalSessionSize(sessionManager), sessionBundle.size)
+            Event.CollectionSaved(sessionManager.normalSessionSize(), sessionBundle.size)
         )
     }
 
@@ -134,7 +136,7 @@ class DefaultCollectionCreationController(
         }
 
         metrics.track(
-            Event.CollectionTabsAdded(normalSessionSize(sessionManager), sessionBundle.size)
+            Event.CollectionTabsAdded(sessionManager.normalSessionSize(), sessionBundle.size)
         )
     }
 
@@ -146,7 +148,7 @@ class DefaultCollectionCreationController(
                 } else {
                     SaveCollectionStep.SelectCollection
                 },
-                defaultCollectionNumber = getDefaultCollectionNumber()
+                defaultCollectionNumber = store.state.tabCollections.getDefaultCollectionNumber()
             )
         )
     }
@@ -155,26 +157,11 @@ class DefaultCollectionCreationController(
         store.dispatch(
             CollectionCreationAction.StepChanged(
                 SaveCollectionStep.NameCollection,
-                getDefaultCollectionNumber()
+                store.state.tabCollections.getDefaultCollectionNumber()
             )
         )
     }
 
-    /**
-     * Returns the new default name recommendation for a collection
-     *
-     * Algorithm: Go through all collections, make a list of their names and keep only the default ones.
-     * Then get the numbers from all these default names, compute the maximum number and add one.
-     */
-    @VisibleForTesting(otherwise = VisibleForTesting.PRIVATE)
-    fun getDefaultCollectionNumber(): Int {
-        return (store.state.tabCollections
-            .map { it.title }
-            .filter { it.matches(Regex("Collection\\s\\d+")) }
-            .map { Integer.valueOf(it.split(" ")[DEFAULT_COLLECTION_NUMBER_POSITION]) }
-            .max() ?: 0) + DEFAULT_INCREMENT_VALUE
-    }
-
     override fun addTabToSelection(tab: Tab) {
         store.dispatch(CollectionCreationAction.TabAdded(tab))
     }
@@ -209,14 +196,4 @@ class DefaultCollectionCreationController(
             SaveCollectionStep.SelectTabs, SaveCollectionStep.RenameCollection -> null
         }
     }
-
-    /**
-     * @return the number of currently active sessions that are neither custom nor private
-     */
-    @VisibleForTesting(otherwise = VisibleForTesting.PRIVATE)
-    fun normalSessionSize(sessionManager: SessionManager): Int {
-        return sessionManager.sessions.filter { session ->
-            (!session.isCustomTabSession() && !session.private)
-        }.size
-    }
 }

app/src/main/java/org/mozilla/fenix/ext/SessionManager.kt

@@ -11,3 +11,12 @@ import mozilla.components.browser.session.SessionManager
  */
 fun SessionManager.sessionsOfType(private: Boolean) =
     sessions.asSequence().filter { it.private == private }
+
+/**
+ * @return the number of currently active sessions that are neither custom nor private
+ */
+fun SessionManager.normalSessionSize(): Int {
+    return this.sessions.filter { session ->
+        (!session.isCustomTabSession() && !session.private)
+    }.size
+}

app/src/main/java/org/mozilla/fenix/ext/TabCollection.kt

@@ -9,6 +9,7 @@ import androidx.annotation.ColorInt
 import androidx.core.content.ContextCompat
 import mozilla.components.feature.tab.collections.TabCollection
 import org.mozilla.fenix.R
+import org.mozilla.fenix.collections.DefaultCollectionCreationController
 import kotlin.math.abs
 
 /**
@@ -22,3 +23,17 @@ fun TabCollection.getIconColor(context: Context): Int {
     iconColors.recycle()
     return color
 }
+
+/**
+ * Returns the new default name recommendation for a collection
+ *
+ * Algorithm: Go through all collections, make a list of their names and keep only the default ones.
+ * Then get the numbers from all these default names, compute the maximum number and add one.
+ */
+fun List<TabCollection>.getDefaultCollectionNumber(): Int {
+    return (this
+        .map { it.title }
+        .filter { it.matches(Regex("Collection\\s\\d+")) }
+        .map { Integer.valueOf(it.split(" ")[DefaultCollectionCreationController.DEFAULT_COLLECTION_NUMBER_POSITION]) }
+        .max() ?: 0) + DefaultCollectionCreationController.DEFAULT_INCREMENT_VALUE
+}

app/src/main/java/org/mozilla/fenix/home/HomeFragment.kt

@@ -101,7 +101,6 @@ import org.mozilla.fenix.onboarding.FenixOnboarding
 import org.mozilla.fenix.settings.SupportUtils
 import org.mozilla.fenix.settings.SupportUtils.SumoTopic.HELP
 import org.mozilla.fenix.settings.deletebrowsingdata.deleteAndQuit
-import org.mozilla.fenix.tabtray.TabTrayDialogFragment
 import org.mozilla.fenix.theme.ThemeManager
 import org.mozilla.fenix.utils.FragmentPreDrawManager
 import org.mozilla.fenix.utils.allowUndo
@@ -920,7 +919,10 @@ class HomeFragment : Fragment() {
     }
 
     private fun openTabTray() {
-        TabTrayDialogFragment.show(parentFragmentManager)
+        findNavController().nav(
+            R.id.homeFragment,
+            HomeFragmentDirections.actionGlobalTabTrayDialogFragment()
+        )
     }
 
     private fun updateTabCounter(browserState: BrowserState) {

app/src/main/java/org/mozilla/fenix/home/sessioncontrol/SessionControlController.kt

@@ -192,8 +192,12 @@ class DefaultSessionControlController(
         metrics.track(Event.CollectionTabRemoved)
 
         if (collection.tabs.size == 1) {
-            val title = activity.resources.getString(R.string.delete_tab_and_collection_dialog_title, collection.title)
+            val title = activity.resources.getString(
-            val message = activity.resources.getString(R.string.delete_tab_and_collection_dialog_message)
+                R.string.delete_tab_and_collection_dialog_title,
+                collection.title
+            )
+            val message =
+                activity.resources.getString(R.string.delete_tab_and_collection_dialog_message)
             showDeleteCollectionPrompt(collection, title, message)
         } else {
             viewLifecycleScope.launch(Dispatchers.IO) {
@@ -208,7 +212,8 @@ class DefaultSessionControlController(
     }
 
     override fun handleDeleteCollectionTapped(collection: TabCollection) {
-        val message = activity.resources.getString(R.string.tab_collection_dialog_message, collection.title)
+        val message =
+            activity.resources.getString(R.string.tab_collection_dialog_message, collection.title)
         showDeleteCollectionPrompt(collection, null, message)
     }
 
@@ -254,8 +259,12 @@ class DefaultSessionControlController(
 
     override fun handleSelectTopSite(url: String, isDefault: Boolean) {
         metrics.track(Event.TopSiteOpenInNewTab)
-        if (isDefault) { metrics.track(Event.TopSiteOpenDefault) }
+        if (isDefault) {
-        if (url == SupportUtils.POCKET_TRENDING_URL) { metrics.track(Event.PocketTopSiteClicked) }
+            metrics.track(Event.TopSiteOpenDefault)
+        }
+        if (url == SupportUtils.POCKET_TRENDING_URL) {
+            metrics.track(Event.PocketTopSiteClicked)
+        }
         addTabUseCase.invoke(
             url = url,
             selectTab = true,
@@ -297,6 +306,13 @@ class DefaultSessionControlController(
         fragmentStore.dispatch(HomeFragmentAction.RemoveTip(tip))
     }
 
+    private fun showTabTrayCollectionCreation() {
+        val directions = HomeFragmentDirections.actionGlobalTabTrayDialogFragment(
+            enterMultiselect = true
+        )
+        navController.nav(R.id.homeFragment, directions)
+    }
+
     private fun showCollectionCreationFragment(
         step: SaveCollectionStep,
         selectedTabIds: Array<String>? = null,
@@ -322,7 +338,7 @@ class DefaultSessionControlController(
     }
 
     override fun handleCreateCollection() {
-        showCollectionCreationFragment(step = SaveCollectionStep.SelectTabs)
+        showTabTrayCollectionCreation()
     }
 
     private fun showShareFragment(data: List<ShareData>) {

app/src/main/java/org/mozilla/fenix/library/bookmarks/BookmarkFragment.kt

@@ -51,7 +51,6 @@ import org.mozilla.fenix.ext.nav
 import org.mozilla.fenix.ext.requireComponents
 import org.mozilla.fenix.ext.toShortUrl
 import org.mozilla.fenix.library.LibraryPageFragment
-import org.mozilla.fenix.tabtray.TabTrayDialogFragment
 import org.mozilla.fenix.utils.allowUndo
 
 /**
@@ -240,7 +239,7 @@ class BookmarkFragment : LibraryPageFragment<BookmarkNode>(), UserInteractionHan
 
     private fun showTabTray() {
         invokePendingDeletion()
-        TabTrayDialogFragment.show(parentFragmentManager)
+        navigate(BookmarkFragmentDirections.actionGlobalTabTrayDialogFragment())
     }
 
     private fun navigate(directions: NavDirections) {

app/src/main/java/org/mozilla/fenix/library/history/HistoryFragment.kt

@@ -44,7 +44,6 @@ import org.mozilla.fenix.ext.requireComponents
 import org.mozilla.fenix.ext.showToolbar
 import org.mozilla.fenix.ext.toShortUrl
 import org.mozilla.fenix.library.LibraryPageFragment
-import org.mozilla.fenix.tabtray.TabTrayDialogFragment
 import org.mozilla.fenix.utils.allowUndo
 
 @SuppressWarnings("TooManyFunctions", "LargeClass")
@@ -207,7 +206,10 @@ class HistoryFragment : LibraryPageFragment<HistoryItem>(), UserInteractionHandl
 
     private fun showTabTray() {
         invokePendingDeletion()
-        TabTrayDialogFragment.show(parentFragmentManager)
+        findNavController().nav(
+            R.id.historyFragment,
+            HistoryFragmentDirections.actionGlobalTabTrayDialogFragment()
+        )
     }
 
     private fun getMultiSelectSnackBarMessage(historyItems: Set<HistoryItem>): String {
@@ -259,7 +261,10 @@ class HistoryFragment : LibraryPageFragment<HistoryItem>(), UserInteractionHandl
                         launch(Main) {
                             viewModel.invalidate()
                             historyStore.dispatch(HistoryFragmentAction.ExitDeletionMode)
-                            showSnackBar(requireView(), getString(R.string.preferences_delete_browsing_data_snackbar))
+                            showSnackBar(
+                                requireView(),
+                                getString(R.string.preferences_delete_browsing_data_snackbar)
+                            )
                         }
                     }
 

app/src/main/java/org/mozilla/fenix/tabtray/CollectionsAdapter.kt

@@ -0,0 +1,72 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+package org.mozilla.fenix.tabtray
+
+import android.view.LayoutInflater
+import android.view.ViewGroup
+import android.widget.CheckedTextView
+import androidx.annotation.VisibleForTesting
+import androidx.core.content.ContextCompat
+import androidx.recyclerview.widget.RecyclerView
+import mozilla.components.support.ktx.android.util.dpToPx
+import org.mozilla.fenix.R
+
+internal class CollectionsAdapter(
+    private val collections: Array<String>,
+    private val onNewCollectionClicked: () -> Unit
+) : RecyclerView.Adapter<CollectionsAdapter.CollectionItemViewHolder>() {
+
+    @VisibleForTesting
+    internal var checkedPosition = 1
+
+    class CollectionItemViewHolder(val textView: CheckedTextView) :
+        RecyclerView.ViewHolder(textView)
+
+    override fun onCreateViewHolder(
+        parent: ViewGroup,
+        viewType: Int
+    ): CollectionItemViewHolder {
+        val textView = LayoutInflater.from(parent.context)
+            .inflate(R.layout.collection_dialog_list_item, parent, false) as CheckedTextView
+        return CollectionItemViewHolder(textView)
+    }
+
+    override fun onBindViewHolder(holder: CollectionItemViewHolder, position: Int) {
+        if (position == 0) {
+            val displayMetrics = holder.textView.context.resources.displayMetrics
+            holder.textView.setPadding(NEW_COLLECTION_PADDING_START.dpToPx(displayMetrics), 0, 0, 0)
+            holder.textView.compoundDrawablePadding =
+                NEW_COLLECTION_DRAWABLE_PADDING.dpToPx(displayMetrics)
+            holder.textView.setCompoundDrawablesWithIntrinsicBounds(
+                ContextCompat.getDrawable(
+                    holder.textView.context,
+                    R.drawable.ic_new
+                ), null, null, null
+            )
+        } else {
+            holder.textView.isChecked = checkedPosition == position
+        }
+
+        holder.textView.setOnClickListener {
+            if (position == 0) {
+                onNewCollectionClicked()
+            } else if (checkedPosition != position) {
+                notifyItemChanged(position)
+                notifyItemChanged(checkedPosition)
+                checkedPosition = position
+            }
+        }
+        holder.textView.text = collections[position]
+    }
+
+    override fun getItemCount() = collections.size
+
+    fun getSelectedCollection() = checkedPosition - 1
+
+    companion object {
+        private const val NEW_COLLECTION_PADDING_START = 24
+        private const val NEW_COLLECTION_DRAWABLE_PADDING = 28
+    }
+}

app/src/main/java/org/mozilla/fenix/tabtray/FenixTabsAdapter.kt

@@ -6,14 +6,19 @@ package org.mozilla.fenix.tabtray
 
 import android.content.Context
 import android.view.LayoutInflater
+import androidx.core.view.isVisible
+import kotlinx.android.synthetic.main.tab_tray_item.view.*
 import mozilla.components.browser.tabstray.TabViewHolder
 import mozilla.components.browser.tabstray.TabsAdapter
 import mozilla.components.concept.tabstray.Tabs
 import mozilla.components.support.images.loader.ImageLoader
 import org.mozilla.fenix.R
+import org.mozilla.fenix.components.metrics.Event
+import org.mozilla.fenix.ext.components
+import org.mozilla.fenix.ext.metrics
 
 class FenixTabsAdapter(
-    context: Context,
+    private val context: Context,
     imageLoader: ImageLoader
 ) : TabsAdapter(
     viewHolderProvider = { parentView ->
@@ -21,11 +26,19 @@ class FenixTabsAdapter(
             LayoutInflater.from(context).inflate(
                 R.layout.tab_tray_item,
                 parentView,
-                false),
+                false
+            ),
             imageLoader
         )
     }
 ) {
+    var tabTrayInteractor: TabTrayInteractor? = null
+
+    private val mode: TabTrayDialogFragmentState.Mode?
+        get() = tabTrayInteractor?.onModeRequested()
+
+    val selectedItems get() = mode?.selectedItems ?: setOf()
+
     var onTabsUpdated: (() -> Unit)? = null
     var tabCount = 0
 
@@ -35,9 +48,53 @@ class FenixTabsAdapter(
         tabCount = tabs.list.size
     }
 
+    override fun onBindViewHolder(
+        holder: TabViewHolder,
+        position: Int,
+        payloads: MutableList<Any>
+    ) {
+        if (payloads.isNullOrEmpty()) {
+            onBindViewHolder(holder, position)
+            return
+        }
+        // Otherwise, item needs to be checked or unchecked
+        val shouldBeChecked =
+            mode is TabTrayDialogFragmentState.Mode.MultiSelect && selectedItems.contains(holder.tab)
+        holder.itemView.checkmark.isVisible = shouldBeChecked
+        holder.itemView.selected_mask.isVisible = shouldBeChecked
+    }
+
     override fun onBindViewHolder(holder: TabViewHolder, position: Int) {
         super.onBindViewHolder(holder, position)
         val newIndex = tabCount - position - 1
         (holder as TabTrayViewHolder).updateAccessibilityRowIndex(holder.itemView, newIndex)
+
+        holder.tab?.let { tab ->
+            val tabIsPrivate =
+                context.components.core.sessionManager.findSessionById(tab.id)?.private == true
+            if (!tabIsPrivate) {
+                holder.itemView.setOnLongClickListener {
+                    if (mode is TabTrayDialogFragmentState.Mode.Normal) {
+                        context.metrics.track(Event.CollectionTabLongPressed)
+                        tabTrayInteractor?.onAddSelectedTab(
+                            tab
+                        )
+                    }
+                    true
+                }
+            }
+
+            holder.itemView.setOnClickListener {
+                if (mode is TabTrayDialogFragmentState.Mode.MultiSelect) {
+                    if (mode?.selectedItems?.contains(tab) == true) {
+                        tabTrayInteractor?.onRemoveSelectedTab(tab = tab)
+                    } else {
+                        tabTrayInteractor?.onAddSelectedTab(tab = tab)
+                    }
+                } else {
+                    tabTrayInteractor?.onOpenTab(tab = tab)
+                }
+            }
+        }
     }
 }

app/src/main/java/org/mozilla/fenix/tabtray/TabTrayController.kt

@@ -9,10 +9,11 @@ import androidx.navigation.NavController
 import kotlinx.coroutines.ExperimentalCoroutinesApi
 import mozilla.components.browser.session.Session
 import mozilla.components.concept.engine.prompt.ShareData
+import mozilla.components.concept.tabstray.Tab
+import mozilla.components.feature.tabs.TabsUseCases
 import org.mozilla.fenix.HomeActivity
-import org.mozilla.fenix.R
 import org.mozilla.fenix.browser.browsingmode.BrowsingMode
-import org.mozilla.fenix.collections.SaveCollectionStep
+import org.mozilla.fenix.components.TabCollectionStorage
 import org.mozilla.fenix.ext.components
 import org.mozilla.fenix.ext.sessionsOfType
 import org.mozilla.fenix.home.HomeFragment
@@ -22,61 +23,81 @@ import org.mozilla.fenix.home.HomeFragment
  *
  * Delegated by View Interactors, handles container business logic and operates changes on it.
  */
+@Suppress("TooManyFunctions")
 interface TabTrayController {
     fun onNewTabTapped(private: Boolean)
     fun onTabTrayDismissed()
     fun onShareTabsClicked(private: Boolean)
-    fun onSaveToCollectionClicked()
+    fun onSaveToCollectionClicked(selectedTabs: Set<Tab>)
     fun onCloseAllTabsClicked(private: Boolean)
+    fun handleBackPressed(): Boolean
+    fun onModeRequested(): TabTrayDialogFragmentState.Mode
+    fun handleAddSelectedTab(tab: Tab)
+    fun handleRemoveSelectedTab(tab: Tab)
+    fun handleOpenTab(tab: Tab)
+    fun handleEnterMultiselect()
 }
 
-@Suppress("TooManyFunctions")
+/**
+ * Default behavior of [TabTrayController]. Other implementations are possible.
+ *
+ * @param activity [HomeActivity] used for context and other Android interactions.
+ * @param navController [NavController] used for navigation.
+ * @param dismissTabTray callback allowing to request this entire Fragment to be dismissed.
+ * @param tabTrayDialogFragmentStore [TabTrayDialogFragmentStore] holding the State for all Views displayed
+ * in this Controller's Fragment.
+ * @param dismissTabTrayAndNavigateHome callback allowing showing an undo snackbar after tab deletion.
+ * @param selectTabUseCase [TabsUseCases.SelectTabUseCase] callback allowing for selecting a tab.
+ * @param registerCollectionStorageObserver callback allowing for registering the [TabCollectionStorage.Observer]
+ * when needed.
+ * @param showChooseCollectionDialog callback allowing saving a list of sessions to an existing collection.
+ * @param showAddNewCollectionDialog callback allowing for saving a list of sessions to a new collection.
+ */
+@Suppress("TooManyFunctions", "LongParameterList")
 class DefaultTabTrayController(
     private val activity: HomeActivity,
     private val navController: NavController,
     private val dismissTabTray: () -> Unit,
     private val dismissTabTrayAndNavigateHome: (String) -> Unit,
-    private val registerCollectionStorageObserver: () -> Unit
+    private val registerCollectionStorageObserver: () -> Unit,
+    private val tabTrayDialogFragmentStore: TabTrayDialogFragmentStore,
+    private val selectTabUseCase: TabsUseCases.SelectTabUseCase,
+    private val showChooseCollectionDialog: (List<Session>) -> Unit,
+    private val showAddNewCollectionDialog: (List<Session>) -> Unit
 ) : TabTrayController {
+    private val tabCollectionStorage = activity.components.core.tabCollectionStorage
+
     override fun onNewTabTapped(private: Boolean) {
         val startTime = activity.components.core.engine.profiler?.getProfilerTime()
         activity.browsingModeManager.mode = BrowsingMode.fromBoolean(private)
         navController.navigate(TabTrayDialogFragmentDirections.actionGlobalHome(focusOnAddressBar = true))
         dismissTabTray()
-        activity.components.core.engine.profiler?.addMarker("DefaultTabTrayController.onNewTabTapped", startTime)
+        activity.components.core.engine.profiler?.addMarker(
+            "DefaultTabTrayController.onNewTabTapped",
+            startTime
+        )
     }
 
     override fun onTabTrayDismissed() {
         dismissTabTray()
     }
 
-    override fun onSaveToCollectionClicked() {
+    override fun onSaveToCollectionClicked(selectedTabs: Set<Tab>) {
-        val tabs = getListOfSessions(false)
+        val sessionList = selectedTabs.map {
-        val tabIds = tabs.map { it.id }.toList().toTypedArray()
+            activity.components.core.sessionManager.findSessionById(it.id) ?: return
-        val tabCollectionStorage = activity.components.core.tabCollectionStorage
-
-        val step = when {
-            // Show the SelectTabs fragment if there are multiple opened tabs to select which tabs
-            // you want to save to a collection.
-            tabs.size > 1 -> SaveCollectionStep.SelectTabs
-            // If there is an existing tab collection, show the SelectCollection fragment to save
-            // the selected tab to a collection of your choice.
-            tabCollectionStorage.cachedTabCollections.isNotEmpty() -> SaveCollectionStep.SelectCollection
-            // Show the NameCollection fragment to create a new collection for the selected tab.
-            else -> SaveCollectionStep.NameCollection
         }
 
-        if (navController.currentDestination?.id == R.id.collectionCreationFragment) return
-
         // Only register the observer right before moving to collection creation
         registerCollectionStorageObserver()
 
-        val directions = TabTrayDialogFragmentDirections.actionGlobalCollectionCreationFragment(
+        when {
-            tabIds = tabIds,
+            tabCollectionStorage.cachedTabCollections.isNotEmpty() -> {
-            saveCollectionStep = step,
+                showChooseCollectionDialog(sessionList)
-            selectedTabIds = tabIds
+            }
-        )
+            else -> {
-        navController.navigate(directions)
+                showAddNewCollectionDialog(sessionList)
+            }
+        }
     }
 
     override fun onShareTabsClicked(private: Boolean) {
@@ -101,8 +122,37 @@ class DefaultTabTrayController(
         dismissTabTrayAndNavigateHome(sessionsToClose)
     }
 
+    override fun handleAddSelectedTab(tab: Tab) {
+        tabTrayDialogFragmentStore.dispatch(TabTrayDialogFragmentAction.AddItemForCollection(tab))
+    }
+
+    override fun handleRemoveSelectedTab(tab: Tab) {
+        tabTrayDialogFragmentStore.dispatch(TabTrayDialogFragmentAction.RemoveItemForCollection(tab))
+    }
+
+    override fun handleBackPressed(): Boolean {
+        return if (tabTrayDialogFragmentStore.state.mode is TabTrayDialogFragmentState.Mode.MultiSelect) {
+            tabTrayDialogFragmentStore.dispatch(TabTrayDialogFragmentAction.ExitMultiSelectMode)
+            true
+        } else {
+            false
+        }
+    }
+
     @VisibleForTesting(otherwise = VisibleForTesting.PRIVATE)
     private fun getListOfSessions(private: Boolean): List<Session> {
         return activity.components.core.sessionManager.sessionsOfType(private = private).toList()
     }
+
+    override fun onModeRequested(): TabTrayDialogFragmentState.Mode {
+        return tabTrayDialogFragmentStore.state.mode
+    }
+
+    override fun handleOpenTab(tab: Tab) {
+        selectTabUseCase.invoke(tab.id)
+    }
+
+    override fun handleEnterMultiselect() {
+        tabTrayDialogFragmentStore.dispatch(TabTrayDialogFragmentAction.EnterMultiSelectMode)
+    }
 }

app/src/main/java/org/mozilla/fenix/tabtray/TabTrayDialogFragment.kt

@@ -4,23 +4,31 @@
 
 package org.mozilla.fenix.tabtray
 
+import android.app.Dialog
 import android.content.res.Configuration
 import android.os.Bundle
 import android.view.LayoutInflater
 import android.view.View
 import android.view.ViewGroup
 import android.view.WindowManager
+import android.widget.EditText
+import androidx.appcompat.app.AlertDialog
 import androidx.appcompat.app.AppCompatDialogFragment
 import androidx.core.view.isVisible
 import androidx.core.view.updatePadding
-import androidx.fragment.app.FragmentManager
 import androidx.lifecycle.lifecycleScope
 import androidx.navigation.fragment.findNavController
+import androidx.navigation.fragment.navArgs
+import androidx.recyclerview.widget.LinearLayoutManager
+import androidx.recyclerview.widget.RecyclerView
 import kotlinx.android.synthetic.main.component_tabstray.view.*
 import kotlinx.android.synthetic.main.component_tabstray_fab.view.*
 import kotlinx.android.synthetic.main.fragment_tab_tray_dialog.*
 import kotlinx.android.synthetic.main.fragment_tab_tray_dialog.view.*
+import kotlinx.coroutines.Dispatchers
+import kotlinx.coroutines.Dispatchers.Main
 import kotlinx.coroutines.ExperimentalCoroutinesApi
+import kotlinx.coroutines.launch
 import mozilla.components.browser.session.Session
 import mozilla.components.browser.state.state.TabSessionState
 import mozilla.components.browser.thumbnails.loader.ThumbnailLoader
@@ -28,24 +36,34 @@ import mozilla.components.feature.tab.collections.TabCollection
 import mozilla.components.feature.tabs.TabsUseCases
 import mozilla.components.feature.tabs.tabstray.TabsFeature
 import mozilla.components.lib.state.ext.consumeFrom
+import mozilla.components.support.base.feature.UserInteractionHandler
 import mozilla.components.support.base.feature.ViewBoundFeatureWrapper
+import mozilla.components.support.ktx.android.view.showKeyboard
 import org.mozilla.fenix.HomeActivity
 import org.mozilla.fenix.R
 import org.mozilla.fenix.browser.BrowserFragmentDirections
 import org.mozilla.fenix.components.FenixSnackbar
+import org.mozilla.fenix.components.StoreProvider
 import org.mozilla.fenix.components.TabCollectionStorage
 import org.mozilla.fenix.components.metrics.Event
 import org.mozilla.fenix.ext.components
+import org.mozilla.fenix.ext.getDefaultCollectionNumber
+import org.mozilla.fenix.ext.metrics
+import org.mozilla.fenix.ext.normalSessionSize
 import org.mozilla.fenix.ext.requireComponents
 import org.mozilla.fenix.ext.settings
+import org.mozilla.fenix.tabtray.TabTrayDialogFragmentState.Mode
 import org.mozilla.fenix.utils.allowUndo
 
 @SuppressWarnings("TooManyFunctions", "LargeClass")
-class TabTrayDialogFragment : AppCompatDialogFragment() {
+class TabTrayDialogFragment : AppCompatDialogFragment(), UserInteractionHandler {
+    private val args by navArgs<TabTrayDialogFragmentArgs>()
+
     private val tabsFeature = ViewBoundFeatureWrapper<TabsFeature>()
     private var _tabTrayView: TabTrayView? = null
     private val tabTrayView: TabTrayView
         get() = _tabTrayView!!
+    private lateinit var tabTrayDialogStore: TabTrayDialogFragmentStore
 
     private val snackbarAnchor: View?
         get() = if (tabTrayView.fabView.new_tab_button.isVisible) tabTrayView.fabView.new_tab_button
@@ -75,6 +93,14 @@ class TabTrayDialogFragment : AppCompatDialogFragment() {
         }
     }
 
+    override fun onCreateDialog(savedInstanceState: Bundle?): Dialog {
+        return object : Dialog(requireContext(), this.theme) {
+            override fun onBackPressed() {
+                this@TabTrayDialogFragment.onBackPressed()
+            }
+        }
+    }
+
     private val removeTabUseCase = object : TabsUseCases.RemoveTabUseCase {
         override fun invoke(sessionId: String) {
             requireContext().components.analytics.metrics.track(Event.ClosedExistingTab)
@@ -109,7 +135,18 @@ class TabTrayDialogFragment : AppCompatDialogFragment() {
         inflater: LayoutInflater,
         container: ViewGroup?,
         savedInstanceState: Bundle?
-    ): View? = inflater.inflate(R.layout.fragment_tab_tray_dialog, container, false)
+    ): View? {
+        tabTrayDialogStore = StoreProvider.get(this) {
+            TabTrayDialogFragmentStore(
+                TabTrayDialogFragmentState(
+                    requireComponents.core.store.state,
+                    if (args.enterMultiselect) Mode.MultiSelect(setOf()) else Mode.Normal
+                )
+            )
+        }
+
+        return inflater.inflate(R.layout.fragment_tab_tray_dialog, container, false)
+    }
 
     override fun onConfigurationChanged(newConfig: Configuration) {
         super.onConfigurationChanged(newConfig)
@@ -140,7 +177,11 @@ class TabTrayDialogFragment : AppCompatDialogFragment() {
                     navController = findNavController(),
                     dismissTabTray = ::dismissAllowingStateLoss,
                     dismissTabTrayAndNavigateHome = ::dismissTabTrayAndNavigateHome,
-                    registerCollectionStorageObserver = ::registerCollectionStorageObserver
+                    registerCollectionStorageObserver = ::registerCollectionStorageObserver,
+                    tabTrayDialogFragmentStore = tabTrayDialogStore,
+                    selectTabUseCase = selectTabUseCase,
+                    showChooseCollectionDialog = ::showChooseCollectionDialog,
+                    showAddNewCollectionDialog = ::showAddNewCollectionDialog
                 )
             ),
             isPrivate = isPrivate,
@@ -188,6 +229,10 @@ class TabTrayDialogFragment : AppCompatDialogFragment() {
         }
 
         consumeFrom(requireComponents.core.store) {
+            tabTrayDialogStore.dispatch(TabTrayDialogFragmentAction.BrowserStateChanged(it))
+        }
+
+        consumeFrom(tabTrayDialogStore) {
             tabTrayView.updateState(it)
         }
     }
@@ -209,7 +254,8 @@ class TabTrayDialogFragment : AppCompatDialogFragment() {
             } ?: return
 
         // Check if this is the last tab of this session type
-        val isLastOpenTab = sessionManager.sessions.filter { snapshot.session.private == it.private }.size == 1
+        val isLastOpenTab =
+            sessionManager.sessions.filter { snapshot.session.private == it.private }.size == 1
 
         if (isLastOpenTab) {
             dismissTabTrayAndNavigateHome(sessionId)
@@ -295,21 +341,101 @@ class TabTrayDialogFragment : AppCompatDialogFragment() {
         }
     }
 
-    companion object {
+    override fun onBackPressed(): Boolean {
-        private const val ELEVATION = 80f
+        if (!tabTrayView.onBackPressed()) {
-        private const val FRAGMENT_TAG = "tabTrayDialogFragment"
+            dismiss()
+        }
+        return true
+    }
 
-        fun show(fragmentManager: FragmentManager) {
+    private fun showChooseCollectionDialog(sessionList: List<Session>) {
-            // If we've killed the fragmentManager. Let's not try to show the tabs tray.
+        context?.let {
-            if (fragmentManager.isDestroyed) {
+            val tabCollectionStorage = it.components.core.tabCollectionStorage
-                return
+            val collections =
-            }
+                tabCollectionStorage.cachedTabCollections.map { it.title }.toTypedArray()
+            val customLayout =
+                LayoutInflater.from(it).inflate(R.layout.add_new_collection_dialog, null)
+            val list = customLayout.findViewById<RecyclerView>(R.id.recycler_view)
+            list.layoutManager = LinearLayoutManager(it)
 
-            // We want to make sure we don't accidentally show the dialog twice if
+            val builder = AlertDialog.Builder(it).setTitle(R.string.tab_tray_select_collection)
-            // a user somehow manages to trigger `show()` twice before we present the dialog.
+                .setView(customLayout)
-            if (fragmentManager.findFragmentByTag(FRAGMENT_TAG) == null) {
+                .setPositiveButton(android.R.string.ok) { dialog, _ ->
-                TabTrayDialogFragment().showNow(fragmentManager, FRAGMENT_TAG)
+                    val selectedCollection =
-            }
+                        (list.adapter as CollectionsAdapter).getSelectedCollection()
+                    val collection = tabCollectionStorage.cachedTabCollections[selectedCollection]
+                    viewLifecycleOwner.lifecycleScope.launch(Dispatchers.IO) {
+                        tabCollectionStorage.addTabsToCollection(collection, sessionList)
+                        it.metrics.track(
+                            Event.CollectionTabsAdded(
+                                it.components.core.sessionManager.normalSessionSize(),
+                                sessionList.size
+                            )
+                        )
+                        launch(Main) {
+                            tabTrayDialogStore.dispatch(TabTrayDialogFragmentAction.ExitMultiSelectMode)
+                            dialog.dismiss()
+                        }
+                    }
+                }.setNegativeButton(android.R.string.cancel) { dialog, _ ->
+                    tabTrayDialogStore.dispatch(TabTrayDialogFragmentAction.ExitMultiSelectMode)
+                    dialog.cancel()
+                }
+
+            val dialog = builder.create()
+            val adapter =
+                CollectionsAdapter(arrayOf(it.getString(R.string.tab_tray_add_new_collection)) + collections) {
+                    dialog.dismiss()
+                    showAddNewCollectionDialog(sessionList)
+                }
+            list.adapter = adapter
+            dialog.show()
         }
     }
+
+    private fun showAddNewCollectionDialog(sessionList: List<Session>) {
+        context?.let {
+            val tabCollectionStorage = it.components.core.tabCollectionStorage
+            val customLayout =
+                LayoutInflater.from(it).inflate(R.layout.name_collection_dialog, null)
+            val collectionNameEditText: EditText =
+                customLayout.findViewById(R.id.collection_name)
+            collectionNameEditText.setText(
+                it.getString(
+                    R.string.create_collection_default_name,
+                    tabCollectionStorage.cachedTabCollections.getDefaultCollectionNumber()
+                )
+            )
+
+            AlertDialog.Builder(it).setTitle(R.string.tab_tray_add_new_collection)
+                .setView(customLayout).setPositiveButton(android.R.string.ok) { dialog, _ ->
+                    viewLifecycleOwner.lifecycleScope.launch(Dispatchers.IO) {
+                        tabCollectionStorage.createCollection(
+                            collectionNameEditText.text.toString(),
+                            sessionList
+                        )
+                        it.metrics.track(
+                            Event.CollectionSaved(
+                                it.components.core.sessionManager.normalSessionSize(),
+                                sessionList.size
+                            )
+                        )
+                        launch(Main) {
+                            tabTrayDialogStore.dispatch(TabTrayDialogFragmentAction.ExitMultiSelectMode)
+                            dialog.dismiss()
+                        }
+                    }
+                }.setNegativeButton(android.R.string.cancel) { dialog, _ ->
+                    tabTrayDialogStore.dispatch(TabTrayDialogFragmentAction.ExitMultiSelectMode)
+                    dialog.cancel()
+                }.create().show().also {
+                    collectionNameEditText.setSelection(0, collectionNameEditText.text.length)
+                    collectionNameEditText.showKeyboard()
+                }
+        }
+    }
+
+    companion object {
+        private const val ELEVATION = 80f
+    }
 }

app/src/main/java/org/mozilla/fenix/tabtray/TabTrayDialogFragmentStore.kt

@@ -0,0 +1,76 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+package org.mozilla.fenix.tabtray
+
+import mozilla.components.browser.state.state.BrowserState
+import mozilla.components.concept.tabstray.Tab
+import mozilla.components.lib.state.Action
+import mozilla.components.lib.state.State
+import mozilla.components.lib.state.Store
+
+/**
+ * The [Store] for holding the [TabTrayDialogFragmentState] and
+ * applying [TabTrayDialogFragmentAction]s.
+ */
+class TabTrayDialogFragmentStore(initialState: TabTrayDialogFragmentState) :
+    Store<TabTrayDialogFragmentState, TabTrayDialogFragmentAction>(
+        initialState,
+        ::tabTrayStateReducer
+    )
+
+/**
+ * Actions to dispatch through the `TabTrayDialogFragmentStore` to modify
+ * `TabTrayDialogFragmentState` through the reducer.
+ */
+sealed class TabTrayDialogFragmentAction : Action {
+    data class BrowserStateChanged(val browserState: BrowserState) : TabTrayDialogFragmentAction()
+    object EnterMultiSelectMode : TabTrayDialogFragmentAction()
+    object ExitMultiSelectMode : TabTrayDialogFragmentAction()
+    data class AddItemForCollection(val item: Tab) : TabTrayDialogFragmentAction()
+    data class RemoveItemForCollection(val item: Tab) : TabTrayDialogFragmentAction()
+}
+
+/**
+ * The state for the Tab Tray Dialog Screen
+ * @property mode Current Mode of Multiselection
+ */
+data class TabTrayDialogFragmentState(val browserState: BrowserState, val mode: Mode) : State {
+    sealed class Mode {
+        open val selectedItems = emptySet<Tab>()
+
+        object Normal : Mode()
+        data class MultiSelect(override val selectedItems: Set<Tab>) : Mode()
+    }
+}
+
+/**
+ * The TabTrayDialogFragmentState Reducer.
+ */
+private fun tabTrayStateReducer(
+    state: TabTrayDialogFragmentState,
+    action: TabTrayDialogFragmentAction
+): TabTrayDialogFragmentState {
+    return when (action) {
+        is TabTrayDialogFragmentAction.BrowserStateChanged -> state.copy(browserState = action.browserState)
+        is TabTrayDialogFragmentAction.AddItemForCollection ->
+            state.copy(mode = TabTrayDialogFragmentState.Mode.MultiSelect(state.mode.selectedItems + action.item))
+        is TabTrayDialogFragmentAction.RemoveItemForCollection -> {
+            val selected = state.mode.selectedItems - action.item
+            state.copy(
+                mode = if (selected.isEmpty()) {
+                    TabTrayDialogFragmentState.Mode.Normal
+                } else {
+                    TabTrayDialogFragmentState.Mode.MultiSelect(selected)
+                }
+            )
+        }
+        is TabTrayDialogFragmentAction.ExitMultiSelectMode -> state.copy(mode = TabTrayDialogFragmentState.Mode.Normal)
+        is TabTrayDialogFragmentAction.EnterMultiSelectMode -> state.copy(
+            mode = TabTrayDialogFragmentState.Mode.MultiSelect(
+                setOf()
+            )
+        )
+    }
+}

app/src/main/java/org/mozilla/fenix/tabtray/TabTrayFragmentInteractor.kt

@@ -4,17 +4,70 @@
 
 package org.mozilla.fenix.tabtray
 
+import mozilla.components.concept.tabstray.Tab
+
+@Suppress("TooManyFunctions")
 interface TabTrayInteractor {
+    /**
+     * Called when user clicks the new tab button.
+     */
     fun onNewTabTapped(private: Boolean)
+
+    /**
+     * Called when tab tray should be dismissed.
+     */
     fun onTabTrayDismissed()
+
+    /**
+     * Called when user clicks the share tabs button.
+     */
     fun onShareTabsClicked(private: Boolean)
-    fun onSaveToCollectionClicked()
+
+    /**
+     * Called when user clicks button to save selected tabs to a collection.
+     */
+    fun onSaveToCollectionClicked(selectedTabs: Set<Tab>)
+
+    /**
+     * Called when user clicks the close all tabs button.
+     */
     fun onCloseAllTabsClicked(private: Boolean)
+
+    /**
+     * Called when the physical back button is clicked.
+     */
+    fun onBackPressed(): Boolean
+
+    /**
+     * Called when a requester needs to know the current mode of the tab tray.
+     */
+    fun onModeRequested(): TabTrayDialogFragmentState.Mode
+
+    /**
+     * Called when a tab should be opened in the browser.
+     */
+    fun onOpenTab(tab: Tab)
+
+    /**
+     * Called when a tab should be selected in multiselect mode.
+     */
+    fun onAddSelectedTab(tab: Tab)
+
+    /**
+     * Called when a tab should be unselected in multiselect mode.
+     */
+    fun onRemoveSelectedTab(tab: Tab)
+
+    /**
+     * Called when multiselect mode should be entered with no tabs selected.
+     */
+    fun onEnterMultiselect()
 }
 
 /**
  * Interactor for the tab tray fragment.
  */
+@Suppress("TooManyFunctions")
 class TabTrayFragmentInteractor(private val controller: TabTrayController) : TabTrayInteractor {
     override fun onNewTabTapped(private: Boolean) {
         controller.onNewTabTapped(private)
@@ -28,11 +81,35 @@ class TabTrayFragmentInteractor(private val controller: TabTrayController) : Tab
         controller.onShareTabsClicked(private)
     }
 
-    override fun onSaveToCollectionClicked() {
+    override fun onSaveToCollectionClicked(selectedTabs: Set<Tab>) {
-        controller.onSaveToCollectionClicked()
+        controller.onSaveToCollectionClicked(selectedTabs)
     }
 
     override fun onCloseAllTabsClicked(private: Boolean) {
         controller.onCloseAllTabsClicked(private)
     }
+
+    override fun onBackPressed(): Boolean {
+        return controller.handleBackPressed()
+    }
+
+    override fun onModeRequested(): TabTrayDialogFragmentState.Mode {
+        return controller.onModeRequested()
+    }
+
+    override fun onAddSelectedTab(tab: Tab) {
+        controller.handleAddSelectedTab(tab)
+    }
+
+    override fun onRemoveSelectedTab(tab: Tab) {
+        controller.handleRemoveSelectedTab(tab)
+    }
+
+    override fun onOpenTab(tab: Tab) {
+        controller.handleOpenTab(tab)
+    }
+
+    override fun onEnterMultiselect() {
+        controller.handleEnterMultiselect()
+    }
 }

app/src/main/java/org/mozilla/fenix/tabtray/TabTrayView.kt

@@ -9,15 +9,18 @@ import android.view.LayoutInflater
 import android.view.View
 import android.view.ViewGroup
 import android.view.accessibility.AccessibilityEvent
+import androidx.annotation.IdRes
 import androidx.cardview.widget.CardView
+import androidx.constraintlayout.widget.ConstraintLayout
+import androidx.constraintlayout.widget.ConstraintSet
 import androidx.core.content.ContextCompat
 import androidx.core.view.isVisible
+import androidx.core.view.updateLayoutParams
 import androidx.lifecycle.LifecycleCoroutineScope
 import androidx.recyclerview.widget.LinearLayoutManager
 import com.google.android.material.bottomsheet.BottomSheetBehavior
 import com.google.android.material.tabs.TabLayout
 import kotlinx.android.extensions.LayoutContainer
-import kotlinx.android.synthetic.main.component_tabstray.*
 import kotlinx.android.synthetic.main.component_tabstray.view.*
 import kotlinx.android.synthetic.main.component_tabstray_fab.view.*
 import kotlinx.android.synthetic.main.tabs_tray_tab_counter.*
@@ -30,6 +33,7 @@ import mozilla.components.browser.menu.item.SimpleBrowserMenuItem
 import mozilla.components.browser.state.selector.normalTabs
 import mozilla.components.browser.state.selector.privateTabs
 import mozilla.components.browser.state.state.BrowserState
+import mozilla.components.support.ktx.android.util.dpToPx
 import org.mozilla.fenix.R
 import org.mozilla.fenix.components.metrics.Event
 import org.mozilla.fenix.ext.components
@@ -51,16 +55,20 @@ class TabTrayView(
     val fabView = LayoutInflater.from(container.context)
         .inflate(R.layout.component_tabstray_fab, container, true)
 
+    private val hasAccessibilityEnabled = container.context.settings().accessibilityServicesEnabled
+
     val view = LayoutInflater.from(container.context)
         .inflate(R.layout.component_tabstray, container, true)
 
-    val isPrivateModeSelected: Boolean get() = view.tab_layout.selectedTabPosition == PRIVATE_TAB_ID
+    private val isPrivateModeSelected: Boolean get() = view.tab_layout.selectedTabPosition == PRIVATE_TAB_ID
 
     private val behavior = BottomSheetBehavior.from(view.tab_wrapper)
 
     private val tabTrayItemMenu: TabTrayItemMenu
     private var menu: BrowserMenu? = null
 
+    private var tabsTouchHelper: TabsTouchHelper
+
     private var hasLoaded = false
 
     override val containerView: View?
@@ -69,8 +77,6 @@ class TabTrayView(
     init {
         container.context.components.analytics.metrics.track(Event.TabsTrayOpened)
 
-        val hasAccessibilityEnabled = view.context.settings().accessibilityServicesEnabled
-
         toggleFabText(isPrivate)
 
         behavior.addBottomSheetCallback(object : BottomSheetBehavior.BottomSheetCallback() {
@@ -126,8 +132,10 @@ class TabTrayView(
             }
             adapter = tabsAdapter
 
-            TabsTouchHelper(tabsAdapter).attachToRecyclerView(this)
+            tabsTouchHelper = TabsTouchHelper(tabsAdapter)
+            tabsTouchHelper.attachToRecyclerView(this)
 
+            tabsAdapter.tabTrayInteractor = interactor
             tabsAdapter.onTabsUpdated = {
                 if (hasAccessibilityEnabled) {
                     tabsAdapter.notifyDataSetChanged()
@@ -158,7 +166,7 @@ class TabTrayView(
                     is TabTrayItemMenu.Item.ShareAllTabs -> interactor.onShareTabsClicked(
                         isPrivateModeSelected
                     )
-                    is TabTrayItemMenu.Item.SaveToCollection -> interactor.onSaveToCollectionClicked()
+                    is TabTrayItemMenu.Item.SaveToCollection -> interactor.onEnterMultiselect()
                     is TabTrayItemMenu.Item.CloseAllTabs -> interactor.onCloseAllTabsClicked(
                         isPrivateModeSelected
                     )
@@ -179,6 +187,10 @@ class TabTrayView(
                 }
         }
 
+        adjustNewTabButtonsForNormalMode()
+    }
+
+    private fun adjustNewTabButtonsForNormalMode() {
         view.tab_tray_new_tab.apply {
             isVisible = hasAccessibilityEnabled
             setOnClickListener {
@@ -214,7 +226,7 @@ class TabTrayView(
         toggleFabText(isPrivateModeSelected)
         filterTabs.invoke(isPrivateModeSelected)
 
-        updateState(view.context.components.core.store.state)
+        updateUINormalMode(view.context.components.core.store.state)
         scrollToTab(view.context.components.core.store.state.selectedTabId)
 
         if (isPrivateModeSelected) {
@@ -230,32 +242,168 @@ class TabTrayView(
     override fun onTabUnselected(tab: TabLayout.Tab?) { /*noop*/
     }
 
-    fun updateState(state: BrowserState) {
+    var mode: TabTrayDialogFragmentState.Mode = TabTrayDialogFragmentState.Mode.Normal
-        view.let {
+        private set
-            val hasNoTabs = if (isPrivateModeSelected) {
-                state.privateTabs.isEmpty()
-            } else {
-                state.normalTabs.isEmpty()
-            }
 
-            view.tab_tray_empty_view.isVisible = hasNoTabs
+    fun updateState(state: TabTrayDialogFragmentState) {
-            if (hasNoTabs) {
+        val oldMode = mode
-                view.tab_tray_empty_view.text = if (isPrivateModeSelected) {
+
-                    view.context.getString(R.string.no_private_tabs_description)
+        if (oldMode::class != state.mode::class && view.context.settings().accessibilityServicesEnabled) {
-                } else {
+            view.announceForAccessibility(
-                    view.context?.getString(R.string.no_open_tabs_description)
+                if (state.mode == TabTrayDialogFragmentState.Mode.Normal) view.context.getString(
+                    R.string.tab_tray_exit_multiselect_content_description
+                ) else view.context.getString(R.string.tab_tray_enter_multiselect_content_description)
+            )
+        }
+
+        mode = state.mode
+        when (state.mode) {
+            TabTrayDialogFragmentState.Mode.Normal -> {
+                view.tabsTray.apply {
+                    tabsTouchHelper.attachToRecyclerView(this)
+                }
+
+                toggleUIMultiselect(multiselect = false)
+
+                updateUINormalMode(state.browserState)
+            }
+            is TabTrayDialogFragmentState.Mode.MultiSelect -> {
+                // Disable swipe to delete while in multiselect
+                tabsTouchHelper.attachToRecyclerView(null)
+
+                toggleUIMultiselect(multiselect = true)
+
+                fabView.new_tab_button.isVisible = false
+                view.tab_tray_new_tab.isVisible = false
+                view.collect_multi_select.isVisible = state.mode.selectedItems.size > 0
+
+                view.multiselect_title.text = view.context.getString(
+                    R.string.tab_tray_multi_select_title,
+                    state.mode.selectedItems.size
+                )
+                view.collect_multi_select.setOnClickListener {
+                    interactor.onSaveToCollectionClicked(state.mode.selectedItems)
+                }
+                view.exit_multi_select.setOnClickListener {
+                    interactor.onBackPressed()
                 }
             }
+        }
 
-            view.tabsTray.visibility = if (hasNoTabs) {
+        if (oldMode.selectedItems != state.mode.selectedItems) {
-                View.INVISIBLE
+            val unselectedItems = oldMode.selectedItems - state.mode.selectedItems
-            } else {
+
-                View.VISIBLE
+            state.mode.selectedItems.union(unselectedItems).forEach { item ->
+                if (view.context.settings().accessibilityServicesEnabled) {
+                    view.announceForAccessibility(
+                        if (unselectedItems.contains(item)) view.context.getString(
+                            R.string.tab_tray_item_unselected_multiselect_content_description,
+                            item.title
+                        ) else view.context.getString(
+                            R.string.tab_tray_item_selected_multiselect_content_description,
+                            item.title
+                        )
+                    )
+                }
+                updateTabsForSelectionChanged(item.id)
             }
-            view.tab_tray_overflow.isVisible = !hasNoTabs
+        }
+    }
 
-            counter_text.text = "${state.normalTabs.size}"
+    private fun ConstraintLayout.setChildWPercent(percentage: Float, @IdRes childId: Int) {
-            updateTabCounterContentDescription(state.normalTabs.size)
+        this.findViewById<View>(childId)?.let {
+            val constraintSet = ConstraintSet()
+            constraintSet.clone(this)
+            constraintSet.constrainPercentWidth(it.id, percentage)
+            constraintSet.applyTo(this)
+            it.requestLayout()
+        }
+    }
+
+    private fun updateUINormalMode(browserState: BrowserState) {
+        val hasNoTabs = if (isPrivateModeSelected) {
+            browserState.privateTabs.isEmpty()
+        } else {
+            browserState.normalTabs.isEmpty()
+        }
+
+        view.tab_tray_empty_view.isVisible = hasNoTabs
+        if (hasNoTabs) {
+            view.tab_tray_empty_view.text = if (isPrivateModeSelected) {
+                view.context.getString(R.string.no_private_tabs_description)
+            } else {
+                view.context?.getString(R.string.no_open_tabs_description)
+            }
+        }
+
+        view.tabsTray.visibility = if (hasNoTabs) {
+            View.INVISIBLE
+        } else {
+            View.VISIBLE
+        }
+        view.tab_tray_overflow.isVisible = !hasNoTabs
+
+        counter_text.text = "${browserState.normalTabs.size}"
+        updateTabCounterContentDescription(browserState.normalTabs.size)
+
+        adjustNewTabButtonsForNormalMode()
+    }
+
+    private fun toggleUIMultiselect(multiselect: Boolean) {
+        view.multiselect_title.isVisible = multiselect
+        view.collect_multi_select.isVisible = multiselect
+        view.exit_multi_select.isVisible = multiselect
+
+        view.topBar.setBackgroundColor(
+            ContextCompat.getColor(
+                view.context,
+                if (multiselect) R.color.accent_normal_theme else R.color.foundation_normal_theme
+            )
+        )
+
+        val displayMetrics = view.context.resources.displayMetrics
+
+        view.handle.updateLayoutParams<ViewGroup.MarginLayoutParams> {
+            height =
+                if (multiselect) MULTISELECT_HANDLE_HEIGHT.dpToPx(displayMetrics) else NORMAL_HANDLE_HEIGHT.dpToPx(
+                    displayMetrics
+                )
+            topMargin = if (multiselect) 0.dpToPx(displayMetrics) else NORMAL_TOP_MARGIN.dpToPx(
+                displayMetrics
+            )
+        }
+
+        view.tab_wrapper.setChildWPercent(
+            if (multiselect) 1F else NORMAL_HANDLE_PERCENT_WIDTH,
+            view.handle.id
+        )
+
+        view.handle.setBackgroundColor(
+            ContextCompat.getColor(
+                view.context,
+                if (multiselect) R.color.accent_normal_theme else R.color.secondary_text_normal_theme
+            )
+        )
+
+        view.tab_layout.isVisible = !multiselect
+        view.tab_tray_empty_view.isVisible = !multiselect
+        view.tab_tray_overflow.isVisible = !multiselect
+        view.tab_layout.isVisible = !multiselect
+    }
+
+    private fun updateTabsForSelectionChanged(itemId: String) {
+        view.tabsTray.apply {
+            val tabs = if (isPrivateModeSelected) {
+                view.context.components.core.store.state.privateTabs
+            } else {
+                view.context.components.core.store.state.normalTabs
+            }
+
+            val selectedBrowserTabIndex = tabs.indexOfFirst { it.id == itemId }
+
+            this.adapter?.notifyItemChanged(
+                selectedBrowserTabIndex, true
+            )
         }
     }
 
@@ -293,6 +441,10 @@ class TabTrayView(
         }
     }
 
+    fun onBackPressed(): Boolean {
+        return interactor.onBackPressed()
+    }
+
     fun scrollToTab(sessionId: String?) {
         view.tabsTray.apply {
             val tabs = if (isPrivateModeSelected) {
@@ -314,6 +466,10 @@ class TabTrayView(
         private const val EXPAND_AT_SIZE = 3
         private const val SLIDE_OFFSET = 0
         private const val SELECTION_DELAY = 500
+        private const val MULTISELECT_HANDLE_HEIGHT = 11
+        private const val NORMAL_HANDLE_HEIGHT = 3
+        private const val NORMAL_TOP_MARGIN = 8
+        private const val NORMAL_HANDLE_PERCENT_WIDTH = 0.1F
     }
 }
 

app/src/main/java/org/mozilla/fenix/tabtray/TabTrayViewHolder.kt

@@ -46,8 +46,7 @@ class TabTrayViewHolder(
     itemView: View,
     private val imageLoader: ImageLoader,
     private val store: BrowserStore = itemView.context.components.core.store,
-    private val metrics: MetricController = itemView.context.components.analytics.metrics,
+    private val metrics: MetricController = itemView.context.components.analytics.metrics
-    val getSelectedTabId: () -> String? = { store.state.selectedTabId }
 ) : TabViewHolder(itemView) {
 
     private val titleView: TextView = itemView.findViewById(R.id.mozac_browser_tabstray_title)
@@ -71,9 +70,6 @@ class TabTrayViewHolder(
         styling: TabsTrayStyling,
         observable: Observable<TabsTray.Observer>
     ) {
-        // This is a hack to workaround a bug in a-c.
-        // https://github.com/mozilla-mobile/android-components/issues/7186
-        val isSelected2 = tab.id == getSelectedTabId()
         this.tab = tab
 
         // Basic text
@@ -82,7 +78,7 @@ class TabTrayViewHolder(
         updateCloseButtonDescription(tab.title)
 
         // Drawables and theme
-        updateBackgroundColor(isSelected2)
+        updateBackgroundColor(isSelected)
 
         if (tab.thumbnail != null) {
             thumbnailView.setImageBitmap(tab.thumbnail)
@@ -144,10 +140,6 @@ class TabTrayViewHolder(
             }
         }
 
-        itemView.setOnClickListener {
-            observable.notifyObservers { onTabSelected(tab) }
-        }
-
         closeView.setOnClickListener {
             observable.notifyObservers { onTabClosed(tab) }
         }

app/src/main/res/layout/add_new_collection_dialog.xml

@@ -0,0 +1,37 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!-- This Source Code Form is subject to the terms of the Mozilla Public
+   - License, v. 2.0. If a copy of the MPL was not distributed with this
+   - file, You can obtain one at http://mozilla.org/MPL/2.0/. -->
+<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
+    xmlns:tools="http://schemas.android.com/tools"
+    android:id="@+id/linear_layout"
+    android:layout_width="match_parent"
+    android:layout_height="wrap_content"
+    android:orientation="vertical">
+
+    <View
+        android:id="@+id/top_divider"
+        android:layout_width="match_parent"
+        android:layout_height="1dp"
+        android:layout_marginTop="16dp"
+        android:background="?neutralFaded" />
+
+    <ScrollView
+        android:id="@+id/scroll_view"
+        android:layout_width="match_parent"
+        android:layout_height="wrap_content">
+
+        <androidx.recyclerview.widget.RecyclerView
+            android:id="@+id/recycler_view"
+            android:layout_width="match_parent"
+            android:layout_height="wrap_content"
+            tools:listitem="@layout/collection_dialog_list_item" />
+    </ScrollView>
+
+    <View
+        android:id="@+id/bottom_divider"
+        android:layout_width="match_parent"
+        android:layout_height="1dp"
+        android:layout_marginBottom="8dp"
+        android:background="?neutralFaded" />
+</LinearLayout>

app/src/main/res/layout/collection_dialog_list_item.xml

@@ -0,0 +1,20 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!-- This Source Code Form is subject to the terms of the Mozilla Public
+   - License, v. 2.0. If a copy of the MPL was not distributed with this
+   - file, You can obtain one at http://mozilla.org/MPL/2.0/. -->
+<CheckedTextView xmlns:android="http://schemas.android.com/apk/res/android"
+    xmlns:app="http://schemas.android.com/apk/res-auto"
+    android:id="@+id/add_new_collection"
+    android:layout_width="match_parent"
+    android:layout_height="wrap_content"
+    android:background="?android:selectableItemBackground"
+    android:drawablePadding="24dp"
+    android:ellipsize="marquee"
+    android:gravity="center_vertical"
+    android:minHeight="?attr/listPreferredItemHeightSmall"
+    android:paddingStart="20dp"
+    android:paddingEnd="?attr/dialogPreferredPadding"
+    android:text="@string/tab_tray_add_new_collection"
+    android:textAppearance="?android:attr/textAppearanceMedium"
+    android:textColor="?primaryText"
+    app:drawableStartCompat="?android:attr/listChoiceIndicatorSingle" />

app/src/main/res/layout/component_tabstray.xml

@@ -2,15 +2,14 @@
 <!-- This Source Code Form is subject to the terms of the Mozilla Public
    - License, v. 2.0. If a copy of the MPL was not distributed with this
    - file, You can obtain one at http://mozilla.org/MPL/2.0/. -->
-
+<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
-<androidx.constraintlayout.widget.ConstraintLayout
-    xmlns:android="http://schemas.android.com/apk/res/android"
     xmlns:app="http://schemas.android.com/apk/res-auto"
     xmlns:mozac="http://schemas.android.com/apk/res-auto"
+    xmlns:tools="http://schemas.android.com/tools"
     android:id="@+id/tab_wrapper"
-    android:layout_height="match_parent"
-    android:layout_width="match_parent"
     style="@style/BottomSheetModal"
+    android:layout_width="match_parent"
+    android:layout_height="match_parent"
     android:backgroundTint="@color/foundation_normal_theme"
     app:layout_behavior="com.google.android.material.bottomsheet.BottomSheetBehavior">
 
@@ -20,81 +19,141 @@
         android:layout_height="3dp"
         android:layout_marginTop="8dp"
         android:background="@color/secondary_text_normal_theme"
-        app:layout_constraintStart_toStartOf="parent"
         app:layout_constraintEnd_toEndOf="parent"
-        app:layout_constraintWidth_percent="0.1"
+        app:layout_constraintStart_toStartOf="parent"
-        app:layout_constraintTop_toTopOf="parent" />
+        app:layout_constraintTop_toTopOf="parent"
+        app:layout_constraintWidth_percent="0.1" />
 
     <TextView
         android:id="@+id/tab_tray_empty_view"
         android:layout_width="0dp"
         android:layout_height="0dp"
+        android:focusable="true"
+        android:focusableInTouchMode="true"
         android:gravity="center_horizontal"
         android:paddingTop="80dp"
         android:text="@string/no_open_tabs_description"
-        android:focusable="true"
-        android:focusableInTouchMode="true"
         android:textColor="?secondaryText"
         android:textSize="16sp"
         app:layout_constraintBottom_toBottomOf="parent"
         app:layout_constraintEnd_toEndOf="parent"
         app:layout_constraintStart_toStartOf="parent"
-        app:layout_constraintTop_toBottomOf="@id/tab_layout" />
+        app:layout_constraintTop_toBottomOf="@id/topBar" />
 
-    <com.google.android.material.tabs.TabLayout
+    <androidx.constraintlayout.widget.ConstraintLayout
-        android:id="@+id/tab_layout"
+        android:id="@+id/topBar"
-        android:layout_width="0dp"
+        android:layout_width="match_parent"
         android:layout_height="80dp"
         android:background="@color/foundation_normal_theme"
-        app:layout_constraintStart_toStartOf="parent"
+        app:layout_constraintTop_toBottomOf="@+id/handle">
-        app:layout_constraintTop_toBottomOf="@+id/handle"
-        app:layout_constraintWidth_percent="0.5"
-        app:tabGravity="fill"
-        app:tabIconTint="@color/tab_icon"
-        app:tabIndicatorColor="@color/accent_normal_theme"
-        app:tabRippleColor="@android:color/transparent">
 
-        <com.google.android.material.tabs.TabItem
+        <ImageButton
-            android:id="@+id/default_tab_item"
+            android:id="@+id/exit_multi_select"
+            android:layout_width="48dp"
+            android:layout_height="48dp"
+            android:layout_marginStart="0dp"
+            android:background="?android:attr/selectableItemBackgroundBorderless"
+            android:contentDescription="@string/tab_tray_close_multiselect_content_description"
+            android:visibility="gone"
+            app:layout_constraintBottom_toBottomOf="@+id/multiselect_title"
+            app:layout_constraintStart_toStartOf="parent"
+            app:layout_constraintTop_toTopOf="@+id/multiselect_title"
+            app:srcCompat="@drawable/ic_close"
+            app:tint="@color/contrast_text_normal_theme" />
+
+        <TextView
+            android:id="@+id/multiselect_title"
             android:layout_width="0dp"
-            android:layout_height="match_parent"
+            android:layout_height="wrap_content"
-            android:contentDescription="@string/tab_header_label"
+            android:layout_marginStart="12dp"
-            android:layout="@layout/tabs_tray_tab_counter"
+            android:textColor="@color/contrast_text_normal_theme"
-            app:tabIconTint="@color/tab_icon" />
+            android:textSize="18sp"
+            app:layout_constraintBottom_toBottomOf="parent"
+            app:layout_constraintEnd_toStartOf="@id/collect_multi_select"
+            app:layout_constraintHorizontal_bias="0.0"
+            app:layout_constraintHorizontal_chainStyle="packed"
+            app:layout_constraintStart_toEndOf="@+id/exit_multi_select"
+            app:layout_constraintTop_toTopOf="parent"
+            tools:text="3 selected" />
 
-        <com.google.android.material.tabs.TabItem
+        <TextView
-            android:id="@+id/private_tab_item"
+            android:id="@+id/collect_multi_select"
+            android:layout_width="wrap_content"
+            android:layout_height="wrap_content"
+            android:layout_marginStart="8dp"
+            android:layout_marginEnd="16dp"
+            android:background="?android:attr/selectableItemBackgroundBorderless"
+            android:contentDescription="@string/tab_tray_collection_button_multiselect_content_description"
+            android:drawablePadding="8dp"
+            android:gravity="center_vertical"
+            android:text="@string/tab_tray_save_to_collection"
+            android:textAllCaps="true"
+            android:textColor="@color/contrast_text_normal_theme"
+            android:textSize="14sp"
+            android:textStyle="bold"
+            android:visibility="gone"
+            app:drawableStartCompat="@drawable/ic_tab_collection"
+            app:drawableTint="@color/contrast_text_normal_theme"
+            app:fontFamily="@font/metropolis_medium"
+            app:layout_constraintBottom_toBottomOf="@id/multiselect_title"
+            app:layout_constraintEnd_toEndOf="parent"
+            app:layout_constraintTop_toTopOf="@id/multiselect_title" />
+
+        <com.google.android.material.tabs.TabLayout
+            android:id="@+id/tab_layout"
             android:layout_width="0dp"
-            android:layout_height="match_parent"
+            android:layout_height="80dp"
-            android:contentDescription="@string/tabs_header_private_tabs_title"
+            android:background="@color/foundation_normal_theme"
-            android:icon="@drawable/ic_private_browsing" />
+            app:layout_constraintStart_toStartOf="parent"
+            app:layout_constraintTop_toTopOf="parent"
+            app:layout_constraintWidth_percent="0.5"
+            app:tabGravity="fill"
+            app:tabIconTint="@color/tab_icon"
+            app:tabIndicatorColor="@color/accent_normal_theme"
+            app:tabRippleColor="@android:color/transparent">
 
-    </com.google.android.material.tabs.TabLayout>
+            <com.google.android.material.tabs.TabItem
+                android:id="@+id/default_tab_item"
+                android:layout_width="0dp"
+                android:layout_height="match_parent"
+                android:contentDescription="@string/tab_header_label"
+                android:layout="@layout/tabs_tray_tab_counter"
+                app:tabIconTint="@color/tab_icon" />
 
-    <ImageButton
+            <com.google.android.material.tabs.TabItem
-        android:id="@+id/tab_tray_new_tab"
+                android:id="@+id/private_tab_item"
-        android:layout_width="48dp"
+                android:layout_width="0dp"
-        android:layout_height="48dp"
+                android:layout_height="match_parent"
-        android:visibility="gone"
+                android:contentDescription="@string/tabs_header_private_tabs_title"
-        android:background="?android:attr/selectableItemBackgroundBorderless"
+                android:icon="@drawable/ic_private_browsing" />
-        android:contentDescription="@string/add_tab"
-        app:srcCompat="@drawable/ic_new"
-        app:layout_constraintTop_toTopOf="@id/tab_layout"
-        app:layout_constraintEnd_toStartOf="@id/tab_tray_overflow"
-        app:layout_constraintBottom_toBottomOf="@id/tab_layout" />
 
-    <ImageButton
+        </com.google.android.material.tabs.TabLayout>
-        android:id="@+id/tab_tray_overflow"
+
-        android:layout_width="48dp"
+        <ImageButton
-        android:layout_height="48dp"
+            android:id="@+id/tab_tray_new_tab"
-        android:background="?android:attr/selectableItemBackgroundBorderless"
+            android:layout_width="48dp"
-        android:contentDescription="@string/open_tabs_menu"
+            android:layout_height="48dp"
-        app:srcCompat="@drawable/ic_menu_tab_tray"
+            android:background="?android:attr/selectableItemBackgroundBorderless"
-        android:layout_marginEnd="0dp"
+            android:contentDescription="@string/add_tab"
-        android:visibility="visible"
+            android:visibility="gone"
-        app:layout_constraintEnd_toEndOf="parent"
+            app:layout_constraintBottom_toBottomOf="@id/tab_layout"
-        app:layout_constraintTop_toTopOf="@id/tab_layout"
+            app:layout_constraintEnd_toStartOf="@id/tab_tray_overflow"
-        app:layout_constraintBottom_toBottomOf="@id/tab_layout" />
+            app:layout_constraintTop_toTopOf="@id/tab_layout"
+            app:srcCompat="@drawable/ic_new" />
+
+        <ImageButton
+            android:id="@+id/tab_tray_overflow"
+            android:layout_width="48dp"
+            android:layout_height="48dp"
+            android:layout_marginEnd="0dp"
+            android:background="?android:attr/selectableItemBackgroundBorderless"
+            android:contentDescription="@string/open_tabs_menu"
+            android:visibility="visible"
+            app:layout_constraintBottom_toBottomOf="@id/tab_layout"
+            app:layout_constraintEnd_toEndOf="parent"
+            app:layout_constraintTop_toTopOf="@id/tab_layout"
+            app:srcCompat="@drawable/ic_menu_tab_tray" />
+    </androidx.constraintlayout.widget.ConstraintLayout>
 
     <View
         android:id="@+id/divider"
@@ -103,14 +162,14 @@
         android:background="@color/tab_tray_item_divider_normal_theme"
         app:layout_constraintEnd_toEndOf="parent"
         app:layout_constraintStart_toStartOf="parent"
-        app:layout_constraintTop_toBottomOf="@+id/tab_layout" />
+        app:layout_constraintTop_toBottomOf="@+id/topBar" />
 
     <androidx.recyclerview.widget.RecyclerView
         android:id="@+id/tabsTray"
         android:layout_width="0dp"
         android:layout_height="0dp"
-        android:paddingBottom="140dp"
         android:clipToPadding="false"
+        android:paddingBottom="140dp"
         android:scrollbars="vertical"
         app:layout_constraintBottom_toBottomOf="parent"
         app:layout_constraintEnd_toEndOf="parent"

app/src/main/res/layout/name_collection_dialog.xml

@@ -0,0 +1,32 @@
+<?xml version="1.0" encoding="utf-8"?>
+<!-- This Source Code Form is subject to the terms of the Mozilla Public
+   - License, v. 2.0. If a copy of the MPL was not distributed with this
+   - file, You can obtain one at http://mozilla.org/MPL/2.0/. -->
+<LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
+    android:layout_width="match_parent"
+    android:layout_height="wrap_content"
+    android:orientation="vertical">
+
+    <TextView
+        android:id="@+id/name_header"
+        android:layout_width="match_parent"
+        android:layout_height="wrap_content"
+        android:layout_marginStart="26dp"
+        android:layout_marginTop="16dp"
+        android:layout_marginEnd="24dp"
+        android:text="@string/tab_tray_add_new_collection_name"
+        android:textAllCaps="true"
+        android:textAppearance="@style/Body16TextStyle"
+        android:textColor="?secondaryText" />
+
+    <EditText
+        android:id="@+id/collection_name"
+        android:layout_width="match_parent"
+        android:layout_height="wrap_content"
+        android:layout_marginStart="24dp"
+        android:layout_marginEnd="24dp"
+        android:backgroundTint="?neutral"
+        android:inputType="text"
+        android:singleLine="true"
+        android:textAlignment="viewStart" />
+</LinearLayout>

app/src/main/res/layout/tab_tray_item.xml

@@ -7,7 +7,9 @@
     android:id="@+id/tab_item"
     android:layout_width="match_parent"
     android:layout_height="88dp"
-    android:focusable="true">
+    android:clickable="true"
+    android:focusable="true"
+    android:foreground="?android:selectableItemBackground">
 
     <ImageButton
         android:id="@+id/play_pause_button"
@@ -36,12 +38,12 @@
 
         <ImageView
             android:id="@+id/default_tab_thumbnail"
-            android:src="@drawable/mozac_ic_globe"
-            android:tint="?tabTrayThumbnailIcon"
-            android:padding="22dp"
-            android:importantForAccessibility="no"
             android:layout_width="match_parent"
-            android:layout_height="match_parent"/>
+            android:layout_height="match_parent"
+            android:importantForAccessibility="no"
+            android:padding="22dp"
+            app:srcCompat="@drawable/mozac_ic_globe"
+            app:tint="?tabTrayThumbnailIcon" />
 
         <mozilla.components.browser.tabstray.thumbnail.TabThumbnailView
             android:id="@+id/mozac_browser_tabstray_thumbnail"
@@ -49,6 +51,26 @@
             android:layout_height="match_parent"
             android:contentDescription="@string/mozac_browser_tabstray_open_tab" />
 
+        <View
+            android:id="@+id/selected_mask"
+            android:layout_width="match_parent"
+            android:layout_height="match_parent"
+            android:background="@color/tab_tray_selected_mask_normal_theme"
+            android:visibility="gone" />
+
+        <ImageView
+            android:id="@+id/checkmark"
+            android:contentDescription="@string/tab_tray_multiselect_selected_content_description"
+            android:layout_width="wrap_content"
+            android:layout_height="wrap_content"
+            android:layout_gravity="center_horizontal|center_vertical"
+            android:background="@drawable/favicon_background"
+            android:backgroundTint="@color/accent_normal_theme"
+            android:elevation="1dp"
+            android:padding="10dp"
+            android:visibility="gone"
+            app:srcCompat="@drawable/mozac_ic_check" />
+
     </androidx.cardview.widget.CardView>
 
     <TextView
@@ -88,10 +110,10 @@
         android:layout_height="match_parent"
         android:background="?android:attr/selectableItemBackgroundBorderless"
         android:contentDescription="@string/close_tab"
-        android:tint="@color/tab_tray_item_text_normal_theme"
         app:layout_constraintEnd_toEndOf="parent"
         app:layout_constraintHorizontal_bias="0.0"
         app:layout_constraintTop_toTopOf="parent"
-        app:srcCompat="@drawable/mozac_ic_close" />
+        app:srcCompat="@drawable/mozac_ic_close"
+        app:tint="@color/tab_tray_item_text_normal_theme" />
 
 </androidx.constraintlayout.widget.ConstraintLayout>

app/src/main/res/navigation/nav_graph.xml

@@ -109,7 +109,12 @@
     <dialog
         android:id="@+id/tabTrayDialogFragment"
         android:name="org.mozilla.fenix.tabtray.TabTrayDialogFragment"
-        tools:layout="@layout/fragment_tab_tray_dialog" />
+        tools:layout="@layout/fragment_tab_tray_dialog">
+        <argument
+            android:name="enterMultiselect"
+            android:defaultValue="false"
+            app:argType="boolean" />
+    </dialog>
 
     <fragment
         android:id="@+id/homeFragment"
@@ -374,13 +379,13 @@
         android:id="@+id/syncedTabsFragment"
         android:name="org.mozilla.fenix.sync.SyncedTabsFragment"
         android:label="@string/synced_tabs"
-        tools:layout="@layout/fragment_synced_tabs"/>
+        tools:layout="@layout/fragment_synced_tabs" />
 
     <fragment
         android:id="@+id/loginExceptionsFragment"
         android:name="org.mozilla.fenix.loginexceptions.LoginExceptionsFragment"
         android:label="@string/preferences_passwords_exceptions"
-        tools:layout="@layout/fragment_exceptions"/>
+        tools:layout="@layout/fragment_exceptions" />
 
     <fragment
         android:id="@+id/loginDetailFragment"

app/src/main/res/values-night/colors.xml

@@ -60,6 +60,7 @@
     <color name="tab_tray_heading_icon_inactive_normal_theme">@color/tab_tray_heading_icon_inactive_dark_theme</color>
     <color name="tab_tray_item_thumbnail_background_normal_theme">@color/tab_tray_item_thumbnail_background_dark_theme</color>
     <color name="tab_tray_item_thumbnail_icon_normal_theme">@color/tab_tray_item_thumbnail_icon_dark_theme</color>
+    <color name="tab_tray_selected_mask_normal_theme">@color/tab_tray_selected_mask_dark_theme</color>
 
     <!--Top site colors -->
     <color name="top_site_background">@color/top_site_background_dark_theme</color>

app/src/main/res/values/colors.xml

@@ -85,6 +85,7 @@
     <color name="tab_tray_heading_icon_inactive_light_theme">@color/ink_20_48a</color>
     <color name="tab_tray_item_thumbnail_background_light_theme">@color/light_grey_10</color>
     <color name="tab_tray_item_thumbnail_icon_light_theme">@color/light_grey_60</color>
+    <color name="tab_tray_selected_mask_light_theme">@color/violet_70_12a</color>
 
     <!-- Dark theme color palette -->
     <color name="primary_text_dark_theme">#FBFBFE</color>
@@ -144,6 +145,7 @@
     <color name="tab_tray_heading_icon_inactive_dark_theme">@color/violet_50_48a</color>
     <color name="tab_tray_item_thumbnail_background_dark_theme">@color/dark_grey_50</color>
     <color name="tab_tray_item_thumbnail_icon_dark_theme">@color/dark_grey_05</color>
+    <color name="tab_tray_selected_mask_dark_theme">@color/violet_50_32a</color>
 
     <!-- Private theme color palette -->
     <color name="primary_text_private_theme">#FBFBFE</color>
@@ -249,6 +251,7 @@
     <color name="tab_tray_heading_icon_inactive_normal_theme">@color/tab_tray_heading_icon_inactive_light_theme</color>
     <color name="tab_tray_item_thumbnail_background_normal_theme">@color/tab_tray_item_thumbnail_background_light_theme</color>
     <color name="tab_tray_item_thumbnail_icon_normal_theme">@color/tab_tray_item_thumbnail_icon_light_theme</color>
+    <color name="tab_tray_selected_mask_normal_theme">@color/tab_tray_selected_mask_light_theme</color>
 
     <!-- Bookmark buttons -->
     <color name="bookmark_favicon_background">#DFDFE3</color>

app/src/main/res/values/strings.xml

@@ -23,6 +23,28 @@
     <string name="open_tab_tray_single">1 open tab. Tap to switch tabs.</string>
     <!-- Message announced to the user when tab tray is selected with 0 or 2+ tabs -->
     <string name="open_tab_tray_plural">%1$s open tabs. Tap to switch tabs.</string>
+    <!-- Tab tray multi select title in app bar. The first parameter is the number of tabs selected -->
+    <string name="tab_tray_multi_select_title">%1$d selected</string>
+    <!-- Label of button in create collection dialog for creating a new collection  -->
+    <string name="tab_tray_add_new_collection">Add new collection</string>
+    <!-- Label of editable text in create collection dialog for naming a new collection  -->
+    <string name="tab_tray_add_new_collection_name">Name</string>
+    <!-- Label of button in save to collection dialog for selecting a current collection  -->
+    <string name="tab_tray_select_collection">Select collection</string>
+    <!-- Content description for close button while in multiselect mode in tab tray -->
+    <string name="tab_tray_close_multiselect_content_description">Exit multiselect mode</string>
+    <!-- Content description for save to collection button while in multiselect mode in tab tray -->
+    <string name="tab_tray_collection_button_multiselect_content_description">Save selected tabs to collection</string>
+    <!-- Content description for checkmark while tab is selected while in multiselect mode in tab tray. The first parameter is the title of the tab selected -->
+    <string name="tab_tray_item_selected_multiselect_content_description">Selected %1$s</string>
+    <!-- Content description when tab is unselected while in multiselect mode in tab tray. The first parameter is the title of the tab unselected -->
+    <string name="tab_tray_item_unselected_multiselect_content_description">Unselected %1$s</string>
+    <!-- Content description announcement when exiting multiselect mode in tab tray -->
+    <string name="tab_tray_exit_multiselect_content_description">Exited multiselect mode</string>
+    <!-- Content description announcement when entering multiselect mode in tab tray -->
+    <string name="tab_tray_enter_multiselect_content_description">Entered multiselect mode, select tabs to save to a collection</string>
+    <!-- Content description on checkmark while tab is selected in multiselect mode in tab tray -->
+    <string name="tab_tray_multiselect_selected_content_description">Selected</string>
 
     <!-- About content. The first parameter is the name of the application. (For example: Fenix) -->
     <string name="about_content">%1$s is produced by Mozilla.</string>
@@ -498,6 +520,8 @@
     <string name="remove_top_site">Remove</string>
     <!-- Postfix for private WebApp titles, placeholder is replaced with app name -->
     <string name="pwa_site_controls_title_private">%1$s (Private Mode)</string>
+    <!-- Button in the current tab tray header in multiselect mode. Saved the selected tabs to a collection when pressed. -->
+    <string name="tab_tray_save_to_collection">Save</string>
 
     <!-- History -->
     <!-- Text for the button to clear all history -->

app/src/main/res/values/styles.xml

@@ -100,6 +100,10 @@
     <style name="NormalTheme" parent="NormalThemeBase" />
 
     <style name="BaseDialogStyle" parent="Theme.MaterialComponents.Dialog.Alert">
+        <item name="colorControlNormal">?primaryText</item>
+        <item name="textColorAlertDialogListItem">?primaryText</item>
+        <item name="android:titleTextStyle">@style/HeaderTextStyle</item>
+        <item name="android:windowTitleStyle">@style/HeaderTextStyle</item>
         <item name="dialogCornerRadius">@dimen/tab_corner_radius</item>
         <item name="android:colorBackground">?above</item>
         <item name="colorAccent">?accent</item>

app/src/test/java/org/mozilla/fenix/collections/DefaultCollectionCreationControllerTest.kt

@@ -210,41 +210,6 @@ class DefaultCollectionCreationControllerTest {
         assertEquals(SaveCollectionStep.SelectCollection, controller.stepBack(SaveCollectionStep.NameCollection))
     }
 
-    @Test
-    fun `GIVEN list of collections WHEN default collection number is required THEN return next default number`() {
-        val collections = mutableListOf<TabCollection>(
-            mockk {
-                every { title } returns "Collection 1"
-            },
-            mockk {
-                every { title } returns "Collection 2"
-            },
-            mockk {
-                every { title } returns "Collection 3"
-            }
-        )
-        state = state.copy(tabCollections = collections)
-        assertEquals(4, controller.getDefaultCollectionNumber())
-
-        collections.add(mockk {
-            every { title } returns "Collection 5"
-        })
-        state = state.copy(tabCollections = collections)
-        assertEquals(6, controller.getDefaultCollectionNumber())
-
-        collections.add(mockk {
-            every { title } returns "Random name"
-        })
-        state = state.copy(tabCollections = collections)
-        assertEquals(6, controller.getDefaultCollectionNumber())
-
-        collections.add(mockk {
-            every { title } returns "Collection 10 10"
-        })
-        state = state.copy(tabCollections = collections)
-        assertEquals(6, controller.getDefaultCollectionNumber())
-    }
-
     @Test
     fun `WHEN adding a new collection THEN dispatch NameCollection step changed`() {
         controller.addNewCollection()
@@ -275,27 +240,6 @@ class DefaultCollectionCreationControllerTest {
         verify { store.dispatch(CollectionCreationAction.StepChanged(SaveCollectionStep.SelectCollection, 2)) }
     }
 
-    @Test
-    fun `normalSessionSize only counts non-private non-custom sessions`() {
-        val normal1 = mockSession()
-        val normal2 = mockSession()
-        val normal3 = mockSession()
-
-        val private1 = mockSession(isPrivate = true)
-        val private2 = mockSession(isPrivate = true)
-
-        val custom1 = mockSession(isCustom = true)
-        val custom2 = mockSession(isCustom = true)
-        val custom3 = mockSession(isCustom = true)
-
-        val privateCustom = mockSession(isPrivate = true, isCustom = true)
-
-        every { sessionManager.sessions } returns listOf(normal1, private1, private2, custom1,
-            normal2, normal3, custom2, custom3, privateCustom)
-
-        assertEquals(3, controller.normalSessionSize(sessionManager))
-    }
-
     private fun mockSession(
         sessionId: String? = null,
         isPrivate: Boolean = false,

app/src/test/java/org/mozilla/fenix/ext/SessionManagerTest.kt

@@ -43,9 +43,44 @@ class SessionManagerTest {
         )
     }
 
+    @Test
+    fun `normalSessionSize only counts non-private non-custom sessions`() {
+        val normal1 = mockSession()
+        val normal2 = mockSession()
+        val normal3 = mockSession()
+
+        val private1 = mockSession(isPrivate = true)
+        val private2 = mockSession(isPrivate = true)
+
+        val custom1 = mockSession(isCustom = true)
+        val custom2 = mockSession(isCustom = true)
+        val custom3 = mockSession(isCustom = true)
+
+        val privateCustom = mockSession(isPrivate = true, isCustom = true)
+
+        val sessionManager = mockSessionManager(
+            listOf(
+                normal1, private1, private2, custom1,
+                normal2, normal3, custom2, custom3, privateCustom
+            )
+        )
+
+        assertEquals(3, sessionManager.normalSessionSize())
+    }
+
     private fun mockSessionManager(sessions: List<Session>): SessionManager {
         val sessionManager: SessionManager = mockk()
         every { sessionManager.sessions } returns sessions
         return sessionManager
     }
+
+    private fun mockSession(
+        sessionId: String? = null,
+        isPrivate: Boolean = false,
+        isCustom: Boolean = false
+    ) = mockk<Session> {
+        sessionId?.let { every { id } returns it }
+        every { private } returns isPrivate
+        every { isCustomTabSession() } returns isCustom
+    }
 }

app/src/test/java/org/mozilla/fenix/ext/TabCollectionTest.kt

@@ -32,6 +32,37 @@ class TabCollectionTest {
         assertNotEquals(defaultColor, mockTabCollection(-123L).getIconColor(testContext))
     }
 
+    @Test
+    fun `GIVEN list of collections WHEN default collection number is required THEN return next default number`() {
+        val collections = mutableListOf<TabCollection>(
+            mockk {
+                every { title } returns "Collection 1"
+            },
+            mockk {
+                every { title } returns "Collection 2"
+            },
+            mockk {
+                every { title } returns "Collection 3"
+            }
+        )
+        assertEquals(4, collections.getDefaultCollectionNumber())
+
+        collections.add(mockk {
+            every { title } returns "Collection 5"
+        })
+        assertEquals(6, collections.getDefaultCollectionNumber())
+
+        collections.add(mockk {
+            every { title } returns "Random name"
+        })
+        assertEquals(6, collections.getDefaultCollectionNumber())
+
+        collections.add(mockk {
+            every { title } returns "Collection 10 10"
+        })
+        assertEquals(6, collections.getDefaultCollectionNumber())
+    }
+
     private fun mockTabCollection(id: Long): TabCollection {
         val collection: TabCollection = mockk()
         every { collection.id } returns id

app/src/test/java/org/mozilla/fenix/home/DefaultSessionControlControllerTest.kt

@@ -336,7 +336,7 @@ class DefaultSessionControlControllerTest {
 
         verify {
             navController.navigate(
-                match<NavDirections> { it.actionId == R.id.action_global_collectionCreationFragment },
+                match<NavDirections> { it.actionId == R.id.action_global_tabTrayDialogFragment },
                 null
             )
         }

app/src/test/java/org/mozilla/fenix/tabtray/CollectionsAdapterTest.kt

@@ -0,0 +1,74 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+package org.mozilla.fenix.tabtray
+
+import android.widget.FrameLayout
+import io.mockk.mockk
+import io.mockk.verify
+import mozilla.components.support.test.robolectric.testContext
+import org.junit.Assert.assertEquals
+import org.junit.Test
+import org.junit.runner.RunWith
+import org.mozilla.fenix.helpers.FenixRobolectricTestRunner
+
+@RunWith(FenixRobolectricTestRunner::class)
+class CollectionsAdapterTest {
+    private val collectionList: Array<String> =
+        arrayOf(
+            "Add new collection",
+            "Collection 1",
+            "Collection 2"
+        )
+    private val onNewCollectionClicked: () -> Unit = mockk(relaxed = true)
+
+    @Test
+    fun `getItemCount should return the correct list size`() {
+        val adapter = CollectionsAdapter(collectionList, onNewCollectionClicked)
+
+        assertEquals(3, adapter.itemCount)
+    }
+
+    @Test
+    fun `getSelectedCollection should account for add new collection when returning right item`() {
+        val adapter = CollectionsAdapter(collectionList, onNewCollectionClicked)
+
+        // first collection by default
+        assertEquals(1, adapter.checkedPosition)
+        assertEquals(0, adapter.getSelectedCollection())
+
+        adapter.checkedPosition = 3
+        assertEquals(2, adapter.getSelectedCollection())
+    }
+
+    @Test
+    fun `creates and binds viewholder`() {
+        val adapter = CollectionsAdapter(collectionList, onNewCollectionClicked)
+
+        val holder1 = adapter.createViewHolder(FrameLayout(testContext), 0)
+        val holder2 = adapter.createViewHolder(FrameLayout(testContext), 0)
+        val holder3 = adapter.createViewHolder(FrameLayout(testContext), 0)
+
+        adapter.bindViewHolder(holder1, 0)
+        adapter.bindViewHolder(holder2, 1)
+        adapter.bindViewHolder(holder3, 2)
+
+        assertEquals("Add new collection", holder1.textView.text)
+        holder1.textView.callOnClick()
+        verify {
+            onNewCollectionClicked()
+        }
+
+        assertEquals(true, holder2.textView.isChecked)
+        assertEquals("Collection 1", holder2.textView.text)
+        holder2.textView.callOnClick()
+        assertEquals(true, holder2.textView.isChecked)
+
+        assertEquals(false, holder3.textView.isChecked)
+        assertEquals("Collection 2", holder3.textView.text)
+        holder3.textView.callOnClick()
+        adapter.bindViewHolder(holder3, 2)
+        assertEquals(true, holder3.textView.isChecked)
+    }
+}

app/src/test/java/org/mozilla/fenix/tabtray/DefaultTabTrayControllerTest.kt

@@ -15,9 +15,12 @@ import io.mockk.mockkStatic
 import io.mockk.slot
 import io.mockk.verify
 import io.mockk.verifyOrder
+import kotlinx.coroutines.ExperimentalCoroutinesApi
 import mozilla.components.browser.session.Session
 import mozilla.components.browser.session.SessionManager
+import mozilla.components.concept.tabstray.Tab
 import mozilla.components.feature.tab.collections.TabCollection
+import mozilla.components.feature.tabs.TabsUseCases
 import org.junit.Assert.assertEquals
 import org.junit.Assert.assertTrue
 import org.junit.Before
@@ -29,20 +32,22 @@ import org.mozilla.fenix.components.TabCollectionStorage
 import org.mozilla.fenix.ext.components
 import org.mozilla.fenix.ext.sessionsOfType
 
+@OptIn(ExperimentalCoroutinesApi::class)
 class DefaultTabTrayControllerTest {
-
     private val activity: HomeActivity = mockk(relaxed = true)
     private val navController: NavController = mockk()
     private val sessionManager: SessionManager = mockk(relaxed = true)
     private val dismissTabTray: (() -> Unit) = mockk(relaxed = true)
     private val dismissTabTrayAndNavigateHome: ((String) -> Unit) = mockk(relaxed = true)
-    private val showUndoSnackbar: ((String, SessionManager.Snapshot) -> Unit) =
-        mockk(relaxed = true)
     private val registerCollectionStorageObserver: (() -> Unit) = mockk(relaxed = true)
+    private val showChooseCollectionDialog: ((List<Session>) -> Unit) = mockk(relaxed = true)
+    private val showAddNewCollectionDialog: ((List<Session>) -> Unit) = mockk(relaxed = true)
     private val tabCollectionStorage: TabCollectionStorage = mockk(relaxed = true)
     private val tabCollection: TabCollection = mockk()
     private val cachedTabCollections: List<TabCollection> = listOf(tabCollection)
     private val currentDestination: NavDestination = mockk(relaxed = true)
+    private val tabTrayFragmentStore: TabTrayDialogFragmentStore = mockk(relaxed = true)
+    private val selectTabUseCase: TabsUseCases.SelectTabUseCase = mockk(relaxed = true)
 
     private lateinit var controller: DefaultTabTrayController
 
@@ -59,28 +64,34 @@ class DefaultTabTrayControllerTest {
     @Before
     fun setUp() {
         mockkStatic("org.mozilla.fenix.ext.SessionManagerKt")
-
         every { activity.components.core.sessionManager } returns sessionManager
         every { activity.components.core.tabCollectionStorage } returns tabCollectionStorage
         every { activity.components.core.engine.profiler } returns mockk(relaxed = true)
+
         every { sessionManager.sessionsOfType(private = true) } returns listOf(session).asSequence()
         every { sessionManager.sessionsOfType(private = false) } returns listOf(nonPrivateSession).asSequence()
         every { sessionManager.createSessionSnapshot(any()) } returns SessionManager.Snapshot.Item(
             session
         )
+        every { sessionManager.findSessionById("1234") } returns session
         every { sessionManager.remove(any()) } just Runs
         every { tabCollectionStorage.cachedTabCollections } returns cachedTabCollections
         every { sessionManager.selectedSession } returns nonPrivateSession
         every { navController.navigate(any<NavDirections>()) } just Runs
         every { navController.currentDestination } returns currentDestination
         every { currentDestination.id } returns R.id.browserFragment
+        every { tabCollection.title } returns "Collection title"
 
         controller = DefaultTabTrayController(
             activity = activity,
             navController = navController,
             dismissTabTray = dismissTabTray,
             dismissTabTrayAndNavigateHome = dismissTabTrayAndNavigateHome,
-            registerCollectionStorageObserver = registerCollectionStorageObserver
+            registerCollectionStorageObserver = registerCollectionStorageObserver,
+            tabTrayDialogFragmentStore = tabTrayFragmentStore,
+            selectTabUseCase = selectTabUseCase,
+            showChooseCollectionDialog = showChooseCollectionDialog,
+            showAddNewCollectionDialog = showAddNewCollectionDialog
         )
     }
 
@@ -120,24 +131,6 @@ class DefaultTabTrayControllerTest {
         }
     }
 
-    @Test
-    fun onSaveToCollectionClicked() {
-        val navDirectionsSlot = slot<NavDirections>()
-        every { navController.navigate(capture(navDirectionsSlot)) } just Runs
-
-        controller.onSaveToCollectionClicked()
-        verify {
-            registerCollectionStorageObserver()
-            navController.navigate(capture(navDirectionsSlot))
-        }
-
-        assertTrue(navDirectionsSlot.isCaptured)
-        assertEquals(
-            R.id.action_global_collectionCreationFragment,
-            navDirectionsSlot.captured.actionId
-        )
-    }
-
     @Test
     fun onShareTabsClicked() {
         val navDirectionsSlot = slot<NavDirections>()
@@ -161,4 +154,73 @@ class DefaultTabTrayControllerTest {
             dismissTabTrayAndNavigateHome(any())
         }
     }
+
+    @Test
+    fun handleBackPressed() {
+        every { tabTrayFragmentStore.state.mode } returns TabTrayDialogFragmentState.Mode.MultiSelect(
+            setOf()
+        )
+        controller.handleBackPressed()
+        verify {
+            tabTrayFragmentStore.dispatch(TabTrayDialogFragmentAction.ExitMultiSelectMode)
+        }
+    }
+
+    @Test
+    fun onModeRequested() {
+        val mode = TabTrayDialogFragmentState.Mode.MultiSelect(
+            setOf()
+        )
+        every { tabTrayFragmentStore.state.mode } returns mode
+        controller.onModeRequested()
+        verify {
+            tabTrayFragmentStore.state.mode
+        }
+    }
+
+    @Test
+    fun handleAddSelectedTab() {
+        val tab = Tab("1234", "mozilla.org")
+        controller.handleAddSelectedTab(tab)
+        verify {
+            tabTrayFragmentStore.dispatch(TabTrayDialogFragmentAction.AddItemForCollection(tab))
+        }
+    }
+
+    @Test
+    fun handleRemoveSelectedTab() {
+        val tab = Tab("1234", "mozilla.org")
+        controller.handleRemoveSelectedTab(tab)
+        verify {
+            tabTrayFragmentStore.dispatch(TabTrayDialogFragmentAction.RemoveItemForCollection(tab))
+        }
+    }
+
+    @Test
+    fun handleOpenTab() {
+        val tab = Tab("1234", "mozilla.org")
+        controller.handleOpenTab(tab)
+        verify {
+            selectTabUseCase.invoke(tab.id)
+        }
+    }
+
+    @Test
+    fun handleEnterMultiselect() {
+        controller.handleEnterMultiselect()
+        verify {
+            tabTrayFragmentStore.dispatch(TabTrayDialogFragmentAction.EnterMultiSelectMode)
+        }
+    }
+
+    @Test
+    fun onSaveToCollectionClicked() {
+        val tab = Tab("1234", "mozilla.org")
+
+        controller.onSaveToCollectionClicked(setOf(tab))
+        verify {
+            registerCollectionStorageObserver()
+            showChooseCollectionDialog(listOf(session))
+        }
+    }
 }

app/src/test/java/org/mozilla/fenix/tabtray/TabTrayDialogFragmentStoreTest.kt

@@ -0,0 +1,145 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+   License, v. 2.0. If a copy of the MPL was not distributed with this
+   file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+package org.mozilla.fenix.tabtray
+
+import kotlinx.coroutines.runBlocking
+import mozilla.components.browser.state.state.BrowserState
+import mozilla.components.browser.state.state.createTab
+import mozilla.components.concept.tabstray.Tab
+import org.junit.Assert.assertEquals
+import org.junit.Assert.assertNotSame
+import org.junit.Test
+
+class TabTrayDialogFragmentStoreTest {
+
+    @Test
+    fun browserStateChange() = runBlocking {
+        val initialState = emptyDefaultState()
+        val store = TabTrayDialogFragmentStore(initialState)
+
+        val newBrowserState = BrowserState(
+            listOf(
+                createTab("https://www.mozilla.org", id = "13256")
+            )
+        )
+
+        store.dispatch(
+            TabTrayDialogFragmentAction.BrowserStateChanged(
+                newBrowserState
+            )
+        ).join()
+
+        assertNotSame(initialState, store.state)
+        assertEquals(
+            store.state.browserState,
+            newBrowserState
+        )
+    }
+
+    @Test
+    fun enterMultiselectMode() = runBlocking {
+        val initialState = emptyDefaultState()
+        val store = TabTrayDialogFragmentStore(initialState)
+
+        store.dispatch(
+            TabTrayDialogFragmentAction.EnterMultiSelectMode
+        ).join()
+
+        assertNotSame(initialState, store.state)
+        assertEquals(
+            store.state.mode,
+            TabTrayDialogFragmentState.Mode.MultiSelect(setOf())
+        )
+    }
+
+    @Test
+    fun exitMultiselectMode() = runBlocking {
+        val initialState = TabTrayDialogFragmentState(
+            browserState = BrowserState(),
+            mode = TabTrayDialogFragmentState.Mode.MultiSelect(setOf())
+        )
+        val store = TabTrayDialogFragmentStore(initialState)
+
+        store.dispatch(
+            TabTrayDialogFragmentAction.ExitMultiSelectMode
+        ).join()
+
+        assertNotSame(initialState, store.state)
+        assertEquals(
+            store.state.mode,
+            TabTrayDialogFragmentState.Mode.Normal
+        )
+        assertEquals(
+            store.state.mode.selectedItems,
+            setOf<Tab>()
+        )
+    }
+
+    @Test
+    fun addItemForCollection() = runBlocking {
+        val initialState = emptyDefaultState()
+        val store = TabTrayDialogFragmentStore(initialState)
+
+        val tab = Tab(id = "1234", url = "mozilla.org")
+        store.dispatch(
+            TabTrayDialogFragmentAction.AddItemForCollection(tab)
+        ).join()
+
+        assertNotSame(initialState, store.state)
+        assertEquals(
+            store.state.mode,
+            TabTrayDialogFragmentState.Mode.MultiSelect(setOf(tab))
+        )
+        assertEquals(
+            store.state.mode.selectedItems,
+            setOf(tab)
+        )
+    }
+
+    @Test
+    fun removeItemForCollection() = runBlocking {
+        val tab = Tab(id = "1234", url = "mozilla.org")
+        val secondTab = Tab(id = "12345", url = "pocket.com")
+
+        val initialState = TabTrayDialogFragmentState(
+            browserState = BrowserState(),
+            mode = TabTrayDialogFragmentState.Mode.MultiSelect(setOf(tab, secondTab))
+        )
+
+        val store = TabTrayDialogFragmentStore(initialState)
+
+        store.dispatch(
+            TabTrayDialogFragmentAction.RemoveItemForCollection(tab)
+        ).join()
+
+        assertNotSame(initialState, store.state)
+        assertEquals(
+            store.state.mode,
+            TabTrayDialogFragmentState.Mode.MultiSelect(setOf(secondTab))
+        )
+        assertEquals(
+            store.state.mode.selectedItems,
+            setOf(secondTab)
+        )
+
+        store.dispatch(
+            TabTrayDialogFragmentAction.RemoveItemForCollection(secondTab)
+        ).join()
+
+        assertEquals(
+            store.state.mode,
+            TabTrayDialogFragmentState.Mode.Normal
+        )
+        assertEquals(
+            store.state.mode.selectedItems,
+            setOf<Tab>()
+        )
+    }
+
+    private fun emptyDefaultState(): TabTrayDialogFragmentState = TabTrayDialogFragmentState(
+        browserState = BrowserState(),
+        mode = TabTrayDialogFragmentState.Mode.Normal
+    )
+}

app/src/test/java/org/mozilla/fenix/tabtray/TabTrayFragmentInteractorTest.kt

@@ -6,6 +6,7 @@ package org.mozilla.fenix.tabtray
 
 import io.mockk.mockk
 import io.mockk.verify
+import mozilla.components.concept.tabstray.Tab
 import org.junit.Test
 
 class TabTrayFragmentInteractorTest {
@@ -38,8 +39,9 @@ class TabTrayFragmentInteractorTest {
 
     @Test
     fun onSaveToCollectionClicked() {
-        interactor.onSaveToCollectionClicked()
+        val tab = Tab("1234", "mozilla.org")
-        verify { controller.onSaveToCollectionClicked() }
+        interactor.onSaveToCollectionClicked(setOf(tab))
+        verify { controller.onSaveToCollectionClicked(setOf(tab)) }
     }
 
     @Test
@@ -50,4 +52,43 @@ class TabTrayFragmentInteractorTest {
         interactor.onCloseAllTabsClicked(private = true)
         verify { controller.onCloseAllTabsClicked(true) }
     }
+
+    @Test
+    fun onBackPressed() {
+        interactor.onBackPressed()
+        verify { controller.handleBackPressed() }
+    }
+
+    @Test
+    fun onModeRequested() {
+        interactor.onModeRequested()
+        verify { controller.onModeRequested() }
+    }
+
+    @Test
+    fun onOpenTab() {
+        val tab = Tab("1234", "mozilla.org")
+        interactor.onOpenTab(tab)
+        verify { controller.handleOpenTab(tab) }
+    }
+
+    @Test
+    fun onAddSelectedTab() {
+        val tab = Tab("1234", "mozilla.org")
+        interactor.onAddSelectedTab(tab)
+        verify { controller.handleAddSelectedTab(tab) }
+    }
+
+    @Test
+    fun onRemoveSelectedTab() {
+        val tab = Tab("1234", "mozilla.org")
+        interactor.onRemoveSelectedTab(tab)
+        verify { controller.handleRemoveSelectedTab(tab) }
+    }
+
+    @Test
+    fun onEnterMultiselect() {
+        interactor.onEnterMultiselect()
+        verify { controller.handleEnterMultiselect() }
+    }
 }

app/src/test/java/org/mozilla/fenix/tabtray/TabTrayViewHolderTest.kt

@@ -109,11 +109,10 @@ class TabTrayViewHolderTest {
         assertEquals("Pause", playPauseButtonView.contentDescription)
     }
 
-    private fun createViewHolder(getSelectedTabId: () -> String? = { null }) = TabTrayViewHolder(
+    private fun createViewHolder() = TabTrayViewHolder(
         view,
         imageLoader = imageLoader,
         store = store,
-        metrics = metrics,
+        metrics = metrics
-        getSelectedTabId = getSelectedTabId
     )
 }