Set the unique_event_id when converting from TouchEvent to WebTouchEvent

ui/events/gestures/motion_event_aura.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.
 
 // MSVC++ requires this to be set before any other includes to get M_PI.
 #define _USE_MATH_DEFINES
 
 #include "ui/events/gestures/motion_event_aura.h"
 
 #include <cmath>
@@ skipping 107 matching lines @@
       break;
     case ET_TOUCH_MOVED:
       UpdateTouch(touch);
       break;
     default:
       NOTREACHED();
       return false;
   }
 
   UpdateCachedAction(touch);
+  set_unique_event_id(touch.unique_event_id());
   set_flags(touch.flags());
   set_event_time(touch.time_stamp() + base::TimeTicks());
   return true;
 }
 
 int MotionEventAura::GetId() const {
   return GetPointerId(0);
 }
 
 void MotionEventAura::CleanupRemovedTouchPoints(const TouchEvent& event) {
@@ skipping 58 matching lines @@
 }
 
 int MotionEventAura::GetIndexFromId(int id) const {
   int index = FindPointerIndexOfId(id);
   DCHECK_GE(index, 0);
   DCHECK_LT(index, static_cast<int>(GetPointerCount()));
   return index;
 }
 
 }  // namespace ui