Implement async touchmove dispatch during scroll

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 "base/logging.h"
 
@@ skipping 316 matching lines @@
                event_to_coalesce,
                &event);
 }
 
 void WebInputEventTraits::Coalesce(const WebInputEvent& event_to_coalesce,
                                    WebInputEvent* event) {
   DCHECK(event);
   Apply(WebInputEventCoalesce(), event->type, event_to_coalesce, event);
 }
 
-bool WebInputEventTraits::IgnoresAckDisposition(
-    blink::WebInputEvent::Type type) {
-  switch (type) {
-    case WebInputEvent::GestureTapDown:
-    case WebInputEvent::GestureShowPress:
-    case WebInputEvent::GestureTapCancel:
-    case WebInputEvent::GestureTap:
-    case WebInputEvent::GesturePinchBegin:
-    case WebInputEvent::GesturePinchEnd:
-    case WebInputEvent::GestureScrollBegin:
-    case WebInputEvent::GestureScrollEnd:
-    case WebInputEvent::TouchCancel:
+bool WebInputEventTraits::IgnoresAckDisposition(const WebInputEvent& event) {
+  switch (event.type) {
     case WebInputEvent::MouseDown:
     case WebInputEvent::MouseUp:
     case WebInputEvent::MouseEnter:
     case WebInputEvent::MouseLeave:
     case WebInputEvent::ContextMenu:
+    case WebInputEvent::GestureScrollBegin:
+    case WebInputEvent::GestureScrollEnd:
+    case WebInputEvent::GestureShowPress:
+    case WebInputEvent::GestureTap:
+    case WebInputEvent::GestureTapUnconfirmed:
+    case WebInputEvent::GestureTapDown:
+    case WebInputEvent::GestureTapCancel:
+    case WebInputEvent::GesturePinchBegin:
+    case WebInputEvent::GesturePinchEnd:
+    case WebInputEvent::TouchCancel:
       return true;
+    case WebInputEvent::TouchStart:
+    case WebInputEvent::TouchMove:
+    case WebInputEvent::TouchEnd:
+      return !static_cast<const WebTouchEvent&>(event).cancelable;

[Rick Byers, 2014/04/23 21:56:17]

Since it's simpler, perhaps we should land my change first
(https://codereview.chromium.org/247433003/), then update this to treat
TouchCancel just like all the other touch event types?

[jdduke (slow), 2014/04/23 22:56:48]

Sounds good.

     default:
-      break;
+      return false;
   }
-  return false;
 }
 
 }  // namespace content