Plumbing for getting FenceTracker timestamps

Change-Id: I1ebee9e42e28658bd3a2b161fdaabb7da756d8f3
diff --git a/include/gui/BufferQueue.h b/include/gui/BufferQueue.h
index 09300a2..fe4b1fa 100644
--- a/include/gui/BufferQueue.h
+++ b/include/gui/BufferQueue.h
@@ -66,6 +66,8 @@
         virtual void onFrameReplaced(const BufferItem& item) override;
         virtual void onBuffersReleased() override;
         virtual void onSidebandStreamChanged() override;
+        virtual bool getFrameTimestamps(uint64_t frameNumber,
+                FrameTimestamps* outTimestamps) const override;
     private:
         // mConsumerListener is a weak reference to the IConsumerListener.  This is
         // the raison d'etre of ProxyConsumerListener.