Add latency measurement system

content/renderer/gpu/input_event_filter.cc

Index: content/renderer/gpu/input_event_filter.cc
diff --git a/content/renderer/gpu/input_event_filter.cc b/content/renderer/gpu/input_event_filter.cc
index 43776fd8184d307b5d42fdddaffaae39599ead16..b2a327358fc254e41a88adce0e9115634dfc9148 100644
--- a/content/renderer/gpu/input_event_filter.cc
+++ b/content/renderer/gpu/input_event_filter.cc
@@ -108,10 +108,15 @@ bool InputEventFilter::OnMessageReceived(const IPC::Message& message) {
 
 // static
 const WebInputEvent* InputEventFilter::CrackMessage(
-    const IPC::Message& message) {
+    const IPC::Message& message, int64* input_number) {
   DCHECK(message.type() == ViewMsg_HandleInputEvent::ID);
 
   PickleIterator iter(message);
+  int64 number;
+  if (!message.ReadInt64(&iter, &number))
+    return NULL;
+  if (input_number)
+    *input_number = number;
   const WebInputEvent* event = NULL;
   IPC::ParamTraits<IPC::WebInputEventPointer>::Read(&message, &iter, &event);
   return event;
@@ -135,7 +140,9 @@ void InputEventFilter::ForwardToHandler(const IPC::Message& message) {
   //
   messages_.push(message);
 
-  handler_.Run(message.routing_id(), CrackMessage(message));
+  int64 input_number;
+  const WebInputEvent* event = CrackMessage(message, &input_number);
+  handler_.Run(message.routing_id(), input_number, event);
 }
 
 void InputEventFilter::SendACK(const IPC::Message& message,
@@ -145,7 +152,7 @@ void InputEventFilter::SendACK(const IPC::Message& message,
   io_loop_->PostTask(
       FROM_HERE,
       base::Bind(&InputEventFilter::SendACKOnIOThread, this,
-                 message.routing_id(), CrackMessage(message)->type,
+                 message.routing_id(), CrackMessage(message, NULL)->type,
                  ack_result));
 }