Closes #472: Integrate feature-session-bundling component.

This will take care of saving and restoring the (`SessionManager`) state.

app/build.gradle

@@ -133,9 +133,12 @@ dependencies {
     implementation Deps.mozilla_feature_session
     implementation Deps.mozilla_feature_toolbar
     implementation Deps.mozilla_feature_tabs
+    implementation Deps.mozilla_feature_findinpage
+    implementation Deps.mozilla_feature_session_bundling
+
     implementation Deps.mozilla_service_fretboard
     implementation Deps.mozilla_service_glean
-    implementation Deps.mozilla_feature_findinpage
+
     implementation Deps.mozilla_support_ktx
 
     implementation Deps.mozilla_ui_colors

app/src/main/java/org/mozilla/fenix/components/Core.kt

@@ -7,6 +7,10 @@ package org.mozilla.fenix.components
 import android.content.Context
 import android.content.SharedPreferences
 import android.preference.PreferenceManager
+import kotlinx.coroutines.Dispatchers
+import kotlinx.coroutines.GlobalScope
+import kotlinx.coroutines.async
+import kotlinx.coroutines.launch
 import mozilla.components.browser.engine.gecko.GeckoEngine
 import mozilla.components.browser.session.SessionManager
 import mozilla.components.browser.session.storage.SessionStorage
@@ -15,10 +19,12 @@ import mozilla.components.concept.engine.DefaultSettings
 import mozilla.components.concept.engine.Engine
 import mozilla.components.concept.engine.EngineSession.TrackingProtectionPolicy
 import mozilla.components.feature.session.HistoryDelegate
+import mozilla.components.feature.session.bundling.SessionBundleStorage
 import mozilla.components.lib.crash.handler.CrashHandlerService
 import org.mozilla.fenix.AppRequestInterceptor
 import org.mozilla.geckoview.GeckoRuntime
 import org.mozilla.geckoview.GeckoRuntimeSettings
+import java.util.concurrent.TimeUnit
 
 /**
  * Component group for all core browser functionality.
@@ -49,6 +55,10 @@ class Core(private val context: Context) {
         GeckoEngine(context, defaultSettings, runtime)
     }
 
+    val sessionStorage by lazy {
+        SessionBundleStorage(context, bundleLifetime = Pair(1, TimeUnit.HOURS))
+    }
+
     /**
      * The session manager component provides access to a centralized registry of
      * all browser sessions (i.e. tabs). It is initialized here to persist and restore
@@ -56,7 +66,24 @@ class Core(private val context: Context) {
      * case all sessions/tabs are closed.
      */
     val sessionManager by lazy {
-        SessionManager(engine)
+        SessionManager(engine).also { sessionManager ->
+            // Restore a previous, still active bundle.
+            GlobalScope.launch(Dispatchers.Main) {
+                val snapshot = async(Dispatchers.IO) {
+                    sessionStorage.restore()?.restoreSnapshot(engine)
+                }
+
+                // There's an active bundle with a snapshot: Feed it into the SessionManager.
+                snapshot.await()?.let { sessionManager.restore(it) }
+
+                // Now that we have restored our previous state (if there's one) let's setup auto saving the state while
+                // the app is used.
+                sessionStorage.autoSave(sessionManager)
+                    .periodicallyInForeground(interval = 30, unit = TimeUnit.SECONDS)
+                    .whenGoingToBackground()
+                    .whenSessionsChange()
+            }
+        }
     }
 
     /**

buildSrc/src/main/java/Dependencies.kt

@@ -76,6 +76,7 @@ object Deps {
     const val mozilla_feature_prompts = "org.mozilla.components:feature-prompts:${Versions.mozilla_android_components}"
     const val mozilla_feature_toolbar = "org.mozilla.components:feature-toolbar:${Versions.mozilla_android_components}"
     const val mozilla_feature_findinpage = "org.mozilla.components:feature-findinpage:${Versions.mozilla_android_components}"
+    const val mozilla_feature_session_bundling = "org.mozilla.components:feature-session-bundling:${Versions.mozilla_android_components}"
 
     const val mozilla_service_fretboard = "org.mozilla.components:service-fretboard:${Versions.mozilla_android_components}"
     const val mozilla_service_glean = "org.mozilla.components:service-glean:${Versions.mozilla_android_components}"