Add latency measurement system

content/renderer/idle_user_detector.cc

Index: content/renderer/idle_user_detector.cc
diff --git a/content/renderer/idle_user_detector.cc b/content/renderer/idle_user_detector.cc
index 1831fa9c8fabf4bf23744acdb5b867e7d488d9cc..587463acd8611b4794949dd97bc2f4d4b2f8da95 100644
--- a/content/renderer/idle_user_detector.cc
+++ b/content/renderer/idle_user_detector.cc
@@ -25,7 +25,8 @@ bool IdleUserDetector::OnMessageReceived(const IPC::Message& message) {
   return false;
 }
 
-void IdleUserDetector::OnHandleInputEvent(const WebKit::WebInputEvent* event,
+void IdleUserDetector::OnHandleInputEvent(int64 input_number,
+                                          const WebKit::WebInputEvent* event,
                                           bool is_keyboard_shortcut) {
   if (GetContentClient()->renderer()->RunIdleHandlerWhenWidgetsHidden()) {
     RenderThreadImpl* render_thread = RenderThreadImpl::current();