Report LatencyInfo through trace buffer

content/browser/renderer_host/input/touch_event_queue.cc

Index: content/browser/renderer_host/input/touch_event_queue.cc
diff --git a/content/browser/renderer_host/input/touch_event_queue.cc b/content/browser/renderer_host/input/touch_event_queue.cc
index 9d0394ef162d034a0f43ebe90cb34969011867de..c480d51a32a433a8b9f37b68e468d074830df7ab 100644
--- a/content/browser/renderer_host/input/touch_event_queue.cc
+++ b/content/browser/renderer_host/input/touch_event_queue.cc
@@ -194,14 +194,11 @@ void TouchEventQueue::PopTouchEventToClient(
   // to the renderer, or touch-events being queued.
   base::AutoReset<bool> dispatching_touch_ack(&dispatching_touch_ack_, true);
 
-  base::TimeTicks now = base::TimeTicks::HighResNow();
   for (WebTouchEventWithLatencyList::const_iterator iter = acked_event->begin(),
        end = acked_event->end();
        iter != end; ++iter) {
     ui::LatencyInfo* latency = const_cast<ui::LatencyInfo*>(&(iter->latency));

[jdduke (slow), 2013/10/01 23:45:31]

Sorry, this isn't directly related to your patch, but this const_cast kills me,
could you go ahead and just make this a regular iterator?  You can change
CoalescedWebTouchEvent to return an iterator(), I believe this is the only place
we use it.

Bonus points for getting rid of begin()/end() calls entirely, and adding a
CoalescedWebTouchEvent::DispatchAckTo(client, renderer_latency_info, ack_result)
that does the dispatch there =/

[Yufeng Shen (Slow to review), 2013/10/04 00:29:51]

Done.

     latency->AddNewLatencyFrom(renderer_latency_info);
-    latency->AddLatencyNumberWithTimestamp(
-        ui::INPUT_EVENT_LATENCY_ACKED_COMPONENT, 0, 0, now, 1);
     client_->OnTouchEventAck((*iter), ack_result);
   }
 }