Add telemetry to track the time an event spent waiting for the main thread.

content/browser/renderer_host/input/immediate_input_router.h

 // Copyright 2013 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef CONTENT_BROWSER_RENDERER_HOST_INPUT_IMMEDIATE_INPUT_ROUTER_H_
 #define CONTENT_BROWSER_RENDERER_HOST_INPUT_IMMEDIATE_INPUT_ROUTER_H_
 
 #include <queue>
 
 #include "base/basictypes.h"
@@ skipping 101 matching lines @@
   void ProcessKeyboardAck(int type, InputEventAckState ack_result);
 
   // Called by ProcessInputEventAck() to process a wheel event ack message.
   // This could result in a task being posted to allow additional wheel
   // input messages to be coalesced.
   void ProcessWheelAck(InputEventAckState ack_result);
 
   // Called by ProcessInputEventAck() to process a gesture event ack message.
   // This validates the gesture for suppression of touchpad taps and sends one
   // previously queued coalesced gesture if it exists.
-  void ProcessGestureAck(int type, InputEventAckState ack_result);
+  void ProcessGestureAck(int type,
+                         InputEventAckState ack_result,

[nduca, 2013/08/15 01:41:04]

here you're changing just the gesture ack but not the others. This is a sign to
me of something not fully thought out... why gesture but not anything else?

+                         const ui::LatencyInfo& latency_info);
 
   // Called on ProcessInputEventAck() to process a touch event ack message.
   // This can result in a gesture event being generated and sent back to the
   // renderer.
   void ProcessTouchAck(InputEventAckState ack_result,
                        const ui::LatencyInfo& latency_info);
 
   int routing_id() const { return routing_id_; }
 
 
@@ skipping 55 matching lines @@
 
   scoped_ptr<TouchEventQueue> touch_event_queue_;
   scoped_ptr<GestureEventFilter> gesture_event_filter_;
 
   DISALLOW_COPY_AND_ASSIGN(ImmediateInputRouter);
 };
 
 }  // namespace content
 
 #endif // CONTENT_BROWSER_RENDERER_HOST_INPUT_IMMEDIATE_INPUT_ROUTER_H_