Fix app headers in settings

Use SettingsPreferenceFragment's method for pinned headers where
possible, and add a frame within the fragment for them to live in
otherwise so that this view doesn't end up on the activity.

Bug: 20886475
Change-Id: I985eb1497744ea50bfabed862e5088eb89df5b61

res/layout/data_usage_summary.xml

@@ -26,6 +26,11 @@
         android:orientation="vertical"
         android:background="@drawable/default_preference_background">
 
+        <FrameLayout
+            android:id="@+id/pinned_header"
+            android:layout_width="match_parent"
+            android:layout_height="wrap_content" />
+
         <include layout="@layout/tab_widget" />
 
         <!-- give an empty content area to make tabhost happy -->

res/layout/manage_applications_apps.xml

@@ -30,6 +30,11 @@
                 android:orientation="vertical"
                 android:visibility="gone">
 
+            <FrameLayout
+                android:id="@+id/pinned_header"
+                android:layout_width="match_parent"
+                android:layout_height="wrap_content" />
+
             <FrameLayout android:layout_width="match_parent"
                     android:layout_height="0px"
                     android:layout_weight="1">