<android.support.design.widget.AppBarLayout
    android:layout_width="match_parent"
    android:layout_height="wrap_content"
    android:theme="@style/AppTheme.AppBarOverlay">

    <android.support.v7.widget.Toolbar
        android:id="@+id/toolbar"
        android:layout_width="match_parent"
        android:layout_height="?attr/actionBarSize"
        android:background="?attr/colorPrimary"
        app:popupTheme="@style/AppTheme.PopupOverlay" />

</android.support.design.widget.AppBarLayout>

<include layout="@layout/content_main" />

....

</android.support.design.widget.CoordinatorLayout>

- Scroll

The app:layout_behavior for the ConstraintLayout is set to @string/appbar_scrolling_view_behavior, which controls how the screen scrolls in relation to the app bar at the top. (This string resource is defined in a generated file called values.xml, which you should not edit.)

```