Store the id of a contributing motion event in GestureEventData

content/browser/renderer_host/input/motion_event_web.cc

 // Copyright 2014 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/browser/renderer_host/input/motion_event_web.h"
 
 #include "base/logging.h"
 
 using blink::WebInputEvent;
 using blink::WebTouchEvent;
@@ skipping 51 matching lines @@
 
 MotionEventWeb::MotionEventWeb(const WebTouchEvent& event)
     : event_(event),
       cached_action_(GetActionFrom(event)),
       cached_action_index_(GetActionIndexFrom(event)) {
   DCHECK_GT(GetPointerCount(), 0U);
 }
 
 MotionEventWeb::~MotionEventWeb() {}
 
+int MotionEventWeb::GetId() const {
+  return 0;
+}
+
 MotionEventWeb::Action MotionEventWeb::GetAction() const {
   return cached_action_;
 }
 
 int MotionEventWeb::GetActionIndex() const { return cached_action_index_; }
 
 size_t MotionEventWeb::GetPointerCount() const { return event_.touchesLength; }
 
 int MotionEventWeb::GetPointerId(size_t pointer_index) const {
   DCHECK_LT(pointer_index, GetPointerCount());
@@ skipping 61 matching lines @@
   WebTouchEvent cancel_event(event_);
 
   cancel_event.type = WebInputEvent::TouchCancel;
   for (size_t i = 0; i < cancel_event.touchesLength; ++i)
     cancel_event.touches[i].state = WebTouchPoint::StateCancelled;
 
   return scoped_ptr<MotionEvent>(new MotionEventWeb(cancel_event));
 }
 
 }  // namespace content