Fix issue #3138926: App's preferences can be lost after onPause()

Change-Id: Icea3d37fab5e47c89c5cbc0adff7bbec898fa93e

core/java/android/app/Activity.java

@@ -1162,7 +1162,6 @@ public class Activity extends ContextThemeWrapper
      */
     protected void onPause() {
         mCalled = true;
-        QueuedWork.waitToFinish();
     }
 
     /**

core/java/android/app/ActivityThread.java

@@ -2265,6 +2265,9 @@ public final class ActivityThread {
             r.activity.mConfigChangeFlags |= configChanges;
             Bundle state = performPauseActivity(token, finished, true);
 
+            // Make sure any pending writes are now committed.
+            QueuedWork.waitToFinish();
+            
             // Tell the activity manager we have paused.
             try {
                 ActivityManagerNative.getDefault().activityPaused(token, state);