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 f59108087c69209783a0f69da546abbd31e5df69..5539445bcc43f65fe7d6bb227eacdb1bfb2167c6 100644
--- a/cc/layer_tree_host_impl.h
+++ b/cc/layer_tree_host_impl.h
@@ -47,6 +47,7 @@ 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 WebKit::WebLatencyInfoImpl& latencyInfo) = 0;
 };
 
 // PinchZoomViewport models the bounds and offset of the viewport that is used during a pinch-zoom operation.
@@ -121,7 +122,7 @@ 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;
@@ -170,6 +171,7 @@ public:
     virtual void setManagedMemoryPolicy(const ManagedMemoryPolicy& policy) OVERRIDE;
     virtual void enforceManagedMemoryPolicy(const ManagedMemoryPolicy& policy) OVERRIDE;
     virtual bool hasImplThread() const OVERRIDE;
+    virtual void onReceivedLatencyInfo(const WebKit::WebLatencyInfoImpl& latency_info) OVERRIDE;
 
     // TileManagerClient implementation.
     virtual void ScheduleManageTiles() OVERRIDE;
@@ -255,6 +257,8 @@ public:
 
     void renderingStats(RenderingStats*) const;
 
+    void setLatencyInfo(const WebKit::WebLatencyInfoImpl& latency_info);
+
     void updateRootScrollLayerImplTransform();
 
     void sendManagedMemoryStats(
@@ -399,6 +403,9 @@ private:
     size_t m_lastSentMemoryVisibleAndNearbyBytes;
     size_t m_lastSentMemoryUseBytes;
 
+    WebKit::WebLatencyInfoImpl m_latencyInfo;
+    bool m_createdFrame;
+
     DISALLOW_COPY_AND_ASSIGN(LayerTreeHostImpl);
 };