Add latency measurement system

content/common/gpu/image_transport_surface_mac.cc

Index: content/common/gpu/image_transport_surface_mac.cc
diff --git a/content/common/gpu/image_transport_surface_mac.cc b/content/common/gpu/image_transport_surface_mac.cc
index 4f888dba9414d26768125d81944f7f7df2f7e571..5b6ef820fb8fea6ed00a1bd2f05639310ade8d46 100644
--- a/content/common/gpu/image_transport_surface_mac.cc
+++ b/content/common/gpu/image_transport_surface_mac.cc
@@ -61,6 +61,7 @@ class IOSurfaceImageTransportSurface : public gfx::NoOpGLSurfaceCGL,
                                  uint32 sync_point) OVERRIDE;
   virtual void OnResizeViewACK() OVERRIDE;
   virtual void OnResize(gfx::Size size) OVERRIDE;
+  virtual void SetLatencyInfo(const WebKit::WebLatencyInfoImpl&) OVERRIDE;
 
  private:
   virtual ~IOSurfaceImageTransportSurface() OVERRIDE;
@@ -295,6 +296,11 @@ void IOSurfaceImageTransportSurface::OnResize(gfx::Size size) {
   CreateIOSurface();
 }
 
+void IOSurfaceImageTransportSurface::SetLatencyInfo(
+    const WebKit::WebLatencyInfoImpl&) {
+  // TODO: implement
+}
+
 void IOSurfaceImageTransportSurface::UnrefIOSurface() {
   // If we have resources to destroy, then make sure that we have a current
   // context which we can use to delete the resources.