Support SurfaceView synchronization.

Add API for fetching the next frame number to be produced by
a given buffer producer. Add an API to SurfaceComposer to 
defer execution of the current transaction until a given frame number. 
Together these may be used to synchronize app drawing and surface 
control updates.

Change-Id: I8e0f4993332ac0199c768c88581a453fefbaff1d
diff --git a/include/gui/Surface.h b/include/gui/Surface.h
index ed2331b..3f46460 100644
--- a/include/gui/Surface.h
+++ b/include/gui/Surface.h
@@ -109,6 +109,9 @@
     // See IGraphicBufferProducer::getConsumerName
     String8 getConsumerName() const;
 
+    // See IGraphicBufferProducer::getNextFrameNumber
+    uint64_t getNextFrameNumber() const;
+
 protected:
     virtual ~Surface();