Add latency measurement system

cc/layer_tree_host_impl.h

Index: cc/layer_tree_host_impl.h
diff --git a/cc/layer_tree_host_impl.h b/cc/layer_tree_host_impl.h
index 25922c8698732081cf7750d02ded974be57e5ea5..3ba1e4ccde27298b2abfc60cf8688c3c5d54ad08 100644
--- a/cc/layer_tree_host_impl.h
+++ b/cc/layer_tree_host_impl.h
@@ -50,6 +50,7 @@ public:
     // Returns true if resources were deleted by this call.
     virtual bool reduceContentsTextureMemoryOnImplThread(size_t limitBytes, int priorityCutoff) = 0;
     virtual void sendManagedMemoryStats() = 0;
+    virtual void onReceivedLatencyInfo(const LatencyInfo& latencyInfo) = 0;
 };
 
 // PinchZoomViewport models the bounds and offset of the viewport that is used during a pinch-zoom operation.
@@ -124,7 +125,7 @@ public:
 
     // InputHandlerClient implementation
     virtual InputHandlerClient::ScrollStatus scrollBegin(gfx::Point, InputHandlerClient::ScrollInputType) OVERRIDE;
-    virtual bool scrollBy(const gfx::Point&, const gfx::Vector2d&) OVERRIDE;
+    virtual bool scrollBy(int64 frame_number, const gfx::Point&, const gfx::Vector2d&) OVERRIDE;
     virtual void scrollEnd() OVERRIDE;
     virtual void pinchGestureBegin() OVERRIDE;
     virtual void pinchGestureUpdate(float, gfx::Point) OVERRIDE;
@@ -183,6 +184,7 @@ public:
     // OutputSurfaceClient implementation.
     virtual void OnVSyncParametersChanged(base::TimeTicks timebase, base::TimeDelta interval) OVERRIDE;
     virtual void OnSendFrameToParentCompositorAck(const CompositorFrameAck&) OVERRIDE;
+    virtual void OnReceivedLatencyInfo(const LatencyInfo& latency_info) OVERRIDE;
 
     // Called from LayerTreeImpl.
     void OnCanDrawStateChangedForTree(LayerTreeImpl*);
@@ -263,6 +265,8 @@ public:
 
     void renderingStats(RenderingStats*) const;
 
+    void setLatencyInfo(const LatencyInfo& latency_info);
+
     void sendManagedMemoryStats(
        size_t memoryVisibleBytes,
        size_t memoryVisibleAndNearbyBytes,
@@ -407,6 +411,9 @@ private:
 
     scoped_ptr<AnimationRegistrar> m_animationRegistrar;
 
+    LatencyInfo m_latencyInfo;
+    bool m_createdFrame;
+
     DISALLOW_COPY_AND_ASSIGN(LayerTreeHostImpl);
 };