Coalesce async touch move events until the ack back from render

content/common/input/web_input_event_traits.cc

 // 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.
 
 #include "content/common/input/web_input_event_traits.h"
 
 #include <bitset>
 #include <limits>
 
 #include "base/logging.h"
@@ skipping 460 matching lines @@
     case WebInputEvent::GestureScrollBegin:
     case WebInputEvent::GestureScrollEnd:
     case WebInputEvent::GestureShowPress:
     case WebInputEvent::GestureTapUnconfirmed:
     case WebInputEvent::GestureTapDown:
     case WebInputEvent::GestureTapCancel:
     case WebInputEvent::GesturePinchBegin:
     case WebInputEvent::GesturePinchEnd:
     case WebInputEvent::TouchCancel:
       return true;
+    // For all touchmove events, we always need an ACK back from render, and
+    // for uncancelable touch move, we will also send a fake ACK.

[tdresser, 2015/03/26 15:25:29]

Hmmm, this is a bit confusing. (Sorry I didn't catch this earlier)

We do ignore the disposition of an uncancelable touchmove, but we still care
about when the ack is sent.

Based on the name of this method, I'd expect TouchMove to be in this list. Can
we put it back? 

[lanwei, 2015/03/27 04:39:42]

Done.

     case WebInputEvent::TouchStart:
-    case WebInputEvent::TouchMove:
     case WebInputEvent::TouchEnd:
       return !static_cast<const WebTouchEvent&>(event).cancelable;
     default:
       return false;
   }
 }
 
 }  // namespace content