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/BufferQueueProducer.h b/include/gui/BufferQueueProducer.h
index 6e16a60..322f2ec 100644
--- a/include/gui/BufferQueueProducer.h
+++ b/include/gui/BufferQueueProducer.h
@@ -170,6 +170,9 @@
     // See IGraphicBufferProducer::getConsumerName
     virtual String8 getConsumerName() const override;
 
+    // See IGraphicBufferProducer::getNextFrameNumber
+    virtual uint64_t getNextFrameNumber() const override;
+
 private:
     // This is required by the IBinder::DeathRecipient interface
     virtual void binderDied(const wp<IBinder>& who);