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/fuelgauge/PowerUsageDetail.java

@@ -464,7 +464,7 @@ public class PowerUsageDetail extends PowerUsageBase implements Button.OnClickLi
             appIcon = getActivity().getPackageManager().getDefaultActivityIcon();
         }
 
-        AppHeader.createAppHeader(getActivity(), appIcon, title, null,
+        AppHeader.createAppHeader(this, appIcon, title, null,
                 mDrainType != DrainType.APP ? android.R.color.white : 0);
     }