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

<?xml version="1.0" encoding="utf-8"?>
<merge 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"
    tools:parentTag="androidx.constraintlayout.widget.ConstraintLayout">

    <org.thoughtcrime.securesms.util.views.DarkOverflowToolbar
        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="Settings" />

    <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" />
</merge>