Fix a crasher on the most visited page when the history is empty.

Make sure that the empty view is always available by setting it
as the content view, and adding the list or grid.  Fixes
http://b/issue?id=2041975
diff --git a/res/layout/empty_history.xml b/res/layout/empty_history.xml
index cbaffd0..8fd3c01 100644
--- a/res/layout/empty_history.xml
+++ b/res/layout/empty_history.xml
@@ -14,7 +14,8 @@
      limitations under the License.
 -->
 
-<TextView xmlns:android="http://schemas.android.com/apk/res/android" 
+<TextView xmlns:android="http://schemas.android.com/apk/res/android"
+    android:id="@+id/empty_view"
     android:layout_width="fill_parent"
     android:layout_height="fill_parent"
     android:text="@string/empty_history"