Javac (at least for 1.7.0_51 on Mac) wants fully qualified class name

It looks like a Javac bug.

Bug: 14255510
Change-Id: Id3899994226049ff77854fd2a13a6d1b687a0392

services/core/java/com/android/server/am/ActivityStackSupervisor.java

@@ -2936,7 +2936,7 @@ public final class ActivityStackSupervisor implements DisplayListener {
         }
     }
 
-    class ActivityContainer extends IActivityContainer.Stub {
+    class ActivityContainer extends android.app.IActivityContainer.Stub {
         final int mStackId;
         IActivityContainerCallback mCallback = null;
         final ActivityStack mStack;