Merge "Add basic integration tests for shelf" into tm-dev

<!-- Extends FrameLayout -->

<com.android.systemui.statusbar.NotificationShelf

    xmlns:android="http://schemas.android.com/apk/res/android"

    android:id="@+id/notificationShelf"

    android:layout_width="match_parent"

    android:layout_height="@dimen/notification_shelf_height"

    android:focusable="true"