Fix ViewTreeObserverTest in Landscape Orientation

Bug 5679517

The content view had a LinearLayout with horizontal orientation,
so the button ended up near the navigation bar which rejected
the simulated pointer event. Change the layout to use vertical
orientation.

The changes in ViewTreeObserverTest are just to remove warnings
and get rid of the testing annotations.

Change-Id: Ibd062336ef1285305fc8238a5a78190a3ec57656
diff --git a/tests/res/layout/viewtreeobserver_layout.xml b/tests/res/layout/viewtreeobserver_layout.xml
index 88112ec..461a4bc 100644
--- a/tests/res/layout/viewtreeobserver_layout.xml
+++ b/tests/res/layout/viewtreeobserver_layout.xml
@@ -16,6 +16,7 @@
 
 <LinearLayout xmlns:android="http://schemas.android.com/apk/res/android"
                 android:id="@+id/linearlayout"
+                android:orientation="vertical"
                 android:layout_width="match_parent"
                 android:layout_height="wrap_content">