Add latency measurement system

content/renderer/gpu/compositor_thread.cc

Index: content/renderer/gpu/compositor_thread.cc
diff --git a/content/renderer/gpu/compositor_thread.cc b/content/renderer/gpu/compositor_thread.cc
index 815d1c221b155cab71ddea083fc165e5350bb124..7c0e7ce95d4b43766ae4391e71f68865ef4776bc 100644
--- a/content/renderer/gpu/compositor_thread.cc
+++ b/content/renderer/gpu/compositor_thread.cc
@@ -152,6 +152,7 @@ void CompositorThread::RemoveInputHandler(int routing_id) {
 
 void CompositorThread::HandleInputEvent(
     int routing_id,
+    int64 input_number,
     const WebInputEvent* input_event) {
   DCHECK_EQ(MessageLoop::current(), thread_.message_loop());
 
@@ -163,7 +164,7 @@ void CompositorThread::HandleInputEvent(
     return;
   }
 
-  it->second->input_handler()->handleInputEvent(*input_event);
+  it->second->input_handler()->handleInputEvent(*input_event, input_number);
 }
 
 }  // namespace content