fenix/app/src/main/res/layout/tab_preview.xml

<?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/. -->
<merge xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto">

    <mozilla.components.browser.tabstray.thumbnail.TabThumbnailView
        android:id="@+id/previewThumbnail"
        android:layout_width="match_parent"
        android:layout_height="match_parent"
        android:background="?tabTrayThumbnailItemBackground" />

    <LinearLayout
        android:id="@+id/fakeToolbar"
        android:layout_width="match_parent"
        android:layout_height="@dimen/browser_toolbar_height"
        android:layout_gravity="bottom"
        android:background="?bottomBarBackground"
        android:elevation="5dp"
        android:foregroundGravity="bottom"
        android:orientation="horizontal">

        <View
            android:id="@+id/toolbar_wrapper"
            android:layout_width="0dp"
            android:layout_height="40dp"
            android:layout_gravity="center"
            android:layout_marginStart="8dp"
            android:layout_marginEnd="0dp"
            android:layout_weight="1"
            android:background="@drawable/home_search_background" />

        <org.mozilla.fenix.components.toolbar.TabCounter
            android:id="@+id/tab_button"
            android:layout_width="48dp"
            android:layout_height="48dp"
            android:layout_gravity="center" />

        <androidx.appcompat.widget.AppCompatImageView
            android:id="@+id/menuButton"
            android:layout_width="36dp"
            android:layout_height="48dp"
            android:layout_gravity="center"
            android:scaleType="center"
            app:srcCompat="@drawable/ic_menu"
            app:tint="?primaryText" />
    </LinearLayout>
</merge>