Signal-Android/app/src/main/res/layout/message_details_activity.xml

<?xml version="1.0" encoding="utf-8"?>
<androidx.constraintlayout.widget.ConstraintLayout xmlns:android="http://schemas.android.com/apk/res/android"
    xmlns:app="http://schemas.android.com/apk/res-auto"
    xmlns:tools="http://schemas.android.com/tools"
    android:layout_width="match_parent"
    android:layout_height="match_parent"
    android:background="@color/signal_background_primary">

    <androidx.appcompat.widget.Toolbar
        android:id="@+id/toolbar"
        android:layout_width="match_parent"
        android:layout_height="56dp"
        android:theme="?attr/settingsToolbarStyle"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toTopOf="parent"
        app:navigationIcon="@drawable/ic_arrow_left_24"
        app:titleTextAppearance="@style/Signal.Text.Title"
        app:navigationContentDescription="@string/DSLSettingsToolbar__navigate_up"
        tools:title="Message Details" />

    <FrameLayout
        android:id="@+id/video_container"
        android:layout_width="0dp"
        android:layout_height="0dp"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@id/toolbar"  />

    <androidx.recyclerview.widget.RecyclerView
        android:id="@+id/message_details_list"
        android:layout_width="0dp"
        android:layout_height="0dp"
        app:layout_constraintBottom_toBottomOf="parent"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@id/toolbar"
        app:layoutManager="androidx.recyclerview.widget.LinearLayoutManager" />

    <View
        android:id="@+id/toolbar_shadow"
        android:layout_width="match_parent"
        android:layout_height="5dp"
        android:alpha="0"
        android:background="@drawable/toolbar_shadow"
        app:layout_constraintEnd_toEndOf="parent"
        app:layout_constraintStart_toStartOf="parent"
        app:layout_constraintTop_toBottomOf="@id/toolbar" />

</androidx.constraintlayout.widget.ConstraintLayout>