Add the actual location coordinates to the touch cancel event

ui/events/gestures/gesture_recognizer_impl.h

 // Copyright (c) 2012 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 UI_EVENTS_GESTURES_GESTURE_RECOGNIZER_IMPL_H_
 #define UI_EVENTS_GESTURES_GESTURE_RECOGNIZER_IMPL_H_
 
 #include <map>
+#include <set>
 #include <vector>
 
 #include "base/memory/linked_ptr.h"
 #include "base/memory/scoped_ptr.h"
 #include "ui/events/event_constants.h"
 #include "ui/events/events_export.h"
 #include "ui/events/gestures/gesture_provider_aura.h"
 #include "ui/events/gestures/gesture_recognizer.h"
 #include "ui/events/gestures/gesture_sequence.h"
 #include "ui/gfx/point.h"
@@ skipping 68 matching lines @@
   // Overridden from ui::GestureSequenceDelegate.
   virtual void DispatchPostponedGestureEvent(GestureEvent* event) OVERRIDE;
 
   // Overridden from GestureProviderAuraClient
   virtual void OnGestureEvent(GestureEvent* event) OVERRIDE;
 
   // Convenience method to find the GestureEventHelper that can dispatch events
   // to a specific |consumer|.
   GestureEventHelper* FindDispatchHelperForConsumer(GestureConsumer* consumer);
 
+  // for all the GestureConsumers in the touches

[tdresser, 2014/08/13 19:57:58]

Capitalize comments, and end them with a period. 
I'm not sure you need these though (see comments in gesture_recognizer_impl.cc)

[lanwei, 2014/08/14 00:38:46]

Done.

+  // create a map from touch id to the touch location
+  std::map<int, gfx::PointF> GroupGestureConsumerWithTouchPoints(
+      std::vector<std::pair<int, GestureConsumer*> >* touches);
+
+  // create a map between the touch_id to the touch point location
+  // by iterating through the pointer_state in GestureConsumer's
+  // GestureProviderAura
+  std::map<int, gfx::PointF> MapTouchIDWithPointLocation(
+      GestureConsumer* consumer);
+
   std::map<GestureConsumer*, GestureSequence*> consumer_sequence_;
   std::map<GestureConsumer*, GestureProviderAura*> consumer_gesture_provider_;
 
   // Both |touch_id_target_| and |touch_id_target_for_gestures_| map a touch-id
   // to its target window.  touch-ids are removed from |touch_id_target_| on
   // ET_TOUCH_RELEASE and ET_TOUCH_CANCEL. |touch_id_target_for_gestures_| are
   // removed in ConsumerDestroyed().
   TouchIdToConsumerMap touch_id_target_;
   TouchIdToConsumerMap touch_id_target_for_gestures_;
 
   std::vector<GestureEventHelper*> helpers_;
 
   bool use_unified_gesture_detector_;
 
   DISALLOW_COPY_AND_ASSIGN(GestureRecognizerImpl);
 };
 
 // Provided only for testing:
 EVENTS_EXPORT void SetGestureRecognizerForTesting(
     GestureRecognizer* gesture_recognizer);
 
 }  // namespace ui
 
 #endif  // UI_EVENTS_GESTURES_GESTURE_RECOGNIZER_IMPL_H_