Plumbing for getting FenceTracker timestamps

Change-Id: I1ebee9e42e28658bd3a2b161fdaabb7da756d8f3
diff --git a/services/surfaceflinger/SurfaceFlinger.h b/services/surfaceflinger/SurfaceFlinger.h
index 8263994..28666e2 100644
--- a/services/surfaceflinger/SurfaceFlinger.h
+++ b/services/surfaceflinger/SurfaceFlinger.h
@@ -440,6 +440,9 @@
             std::vector<OccupancyTracker::Segment>&& history);
     void dumpBufferingStats(String8& result) const;
 
+    bool getFrameTimestamps(const Layer& layer, uint64_t frameNumber,
+            FrameTimestamps* outTimestamps);
+
     /* ------------------------------------------------------------------------
      * Attributes
      */