Resume RT-animations after a pauseSurface

Bug: 18203577

The issue occurs as a result of performTraversals() both doing
a window relayout call *and* early-returning because it's not dirty.

To fix this pauseSurface() returns whether or not the RT-side is
"dirty" to force ViewRootImpl to do a draw even if mDirty is
otherwise empty.

Change-Id: I534f367e75d18d273ebf14df3927f5c464ef6bef
diff --git a/libs/hwui/renderthread/RenderThread.h b/libs/hwui/renderthread/RenderThread.h
index c461f3a..4126d02 100644
--- a/libs/hwui/renderthread/RenderThread.h
+++ b/libs/hwui/renderthread/RenderThread.h
@@ -80,7 +80,7 @@
 
     // Mimics android.view.Choreographer
     void postFrameCallback(IFrameCallback* callback);
-    void removeFrameCallback(IFrameCallback* callback);
+    bool removeFrameCallback(IFrameCallback* callback);
     // If the callback is currently registered, it will be pushed back until
     // the next vsync. If it is not currently registered this does nothing.
     void pushBackFrameCallback(IFrameCallback* callback);