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

src/com/android/settings/notification/AppNotificationSettings.java

@@ -84,7 +84,7 @@ public class AppNotificationSettings extends SettingsPreferenceFragment {
         }
         mCreated = true;
         if (mAppRow == null) return;
-        AppHeader.createAppHeader(getActivity(), mAppRow.icon, mAppRow.label,
+        AppHeader.createAppHeader(this, mAppRow.icon, mAppRow.label,
                 mAppRow.settingsIntent);
     }