Make sure send one WebTouchEvent ack per ui::TouchEvent

ui/events/blink/blink_event_util.cc

 // Copyright 2015 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.
 
 // MSVC++ requires this to be set before any other includes to get M_PI.
 #define _USE_MATH_DEFINES
 
 #include "ui/events/blink/blink_event_util.h"
 
 #include <cmath>
@@ skipping 35 matching lines @@
 
 // Note that |is_action_pointer| is meaningful only in the context of
 // |ACTION_POINTER_UP| and |ACTION_POINTER_DOWN|; other actions map directly to
 // WebTouchPoint::State.
 WebTouchPoint::State ToWebTouchPointState(const MotionEvent& event,
                                           size_t pointer_index) {
   switch (event.GetAction()) {
     case MotionEvent::ACTION_DOWN:
       return WebTouchPoint::StatePressed;
     case MotionEvent::ACTION_MOVE:
-      return WebTouchPoint::StateMoved;
+      return static_cast<int>(pointer_index) == event.GetActionIndex()

[tdresser, 2015/05/04 20:39:37]

GetActionIndex is only valid if |GetAction()| returns ACTION_POINTER_UP or
ACTION_POINTER_DOWN.

+                 ? WebTouchPoint::StateMoved
+                 : WebTouchPoint::StateStationary;
     case MotionEvent::ACTION_UP:
       return WebTouchPoint::StateReleased;
     case MotionEvent::ACTION_CANCEL:
-      return WebTouchPoint::StateCancelled;
+      return static_cast<int>(pointer_index) == event.GetActionIndex()
+                 ? WebTouchPoint::StateCancelled
+                 : WebTouchPoint::StateStationary;
     case MotionEvent::ACTION_POINTER_DOWN:
       return static_cast<int>(pointer_index) == event.GetActionIndex()
                  ? WebTouchPoint::StatePressed
                  : WebTouchPoint::StateStationary;
     case MotionEvent::ACTION_POINTER_UP:
       return static_cast<int>(pointer_index) == event.GetActionIndex()
                  ? WebTouchPoint::StateReleased
                  : WebTouchPoint::StateStationary;
   }
   NOTREACHED() << "Invalid MotionEvent::Action.";
@@ skipping 225 matching lines @@
 }
 
 WebGestureEvent CreateWebGestureEventFromGestureEventData(
     const GestureEventData& data) {
   return CreateWebGestureEvent(data.details, data.time - base::TimeTicks(),
                                gfx::PointF(data.x, data.y),
                                gfx::PointF(data.raw_x, data.raw_y), data.flags);
 }
 
 }  // namespace ui