Add latency measurement system

ui/compositor/compositor.cc

Index: ui/compositor/compositor.cc
diff --git a/ui/compositor/compositor.cc b/ui/compositor/compositor.cc
index 43a6e4402642dc96d5c575ca2c4ff92b9057ceeb..d22cc94f83bf086f67bc0558ed0e205557540c70 100644
--- a/ui/compositor/compositor.cc
+++ b/ui/compositor/compositor.cc
@@ -303,6 +303,7 @@ Compositor::Compositor(CompositorDelegate* delegate,
       device_scale_factor_(0.0f),
       last_started_frame_(0),
       last_ended_frame_(0),
+      frame_number_(0),
       disable_schedule_composite_(false),
       compositor_lock_(NULL) {
   root_web_layer_ = cc::Layer::create();
@@ -547,6 +548,21 @@ void Compositor::didCompleteSwapBuffers() {
   NotifyEnd();
 }
 
+void Compositor::onReceivedLatencyInfo(
+    const cc::LatencyInfo& latencyInfo) {
+  FOR_EACH_OBSERVER(CompositorObserver,
+                    observer_list_,
+                    OnReceivedLatencyInfo(this, latencyInfo));
+}
+
+int64 Compositor::SetInputNumber(int64 input_number) {
+  cc::LatencyInfo browser_latency_info;
+  browser_latency_info.rendererMainFrameNumber = ++frame_number_;
+  browser_latency_info.inputNumber = input_number;
+  host_->setLatencyInfo(browser_latency_info);
+  return frame_number_;
+}
+
 void Compositor::scheduleComposite() {
   if (!disable_schedule_composite_)
     ScheduleDraw();