Set the unique_event_id when converting from TouchEvent to WebTouchEvent

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.
 
 // MSVC++ requires this to be set before any other includes to get M_PI.
 #define _USE_MATH_DEFINES
 
 #include "content/browser/renderer_host/input/motion_event_web.h"
 
 #include <cmath>
 
 #include "base/logging.h"
 #include "content/browser/renderer_host/input/web_input_event_util.h"
 #include "content/common/input/web_touch_event_traits.h"
+#include "ui/events/base_event_utils.h"
 
 using blink::WebInputEvent;
 using blink::WebTouchEvent;
 using blink::WebTouchPoint;
 
 namespace content {
 namespace {
 
 ui::MotionEvent::Action GetActionFrom(const WebTouchEvent& event) {
   DCHECK(event.touchesLength);
@@ skipping 31 matching lines @@
       return i;
   }
   return -1;
 }
 
 }  // namespace
 
 MotionEventWeb::MotionEventWeb(const WebTouchEvent& event)
     : event_(event),
       cached_action_(GetActionFrom(event)),
-      cached_action_index_(GetActionIndexFrom(event)) {
+      cached_action_index_(GetActionIndexFrom(event)),
+      unique_event_id_(ui::GetNextTouchEventId()) {

[jdduke (slow), 2015/04/17 20:30:01]

Shouldn't this ID come from event.uniqueTouchEventId?

[lanwei, 2015/04/20 19:58:59]

This WebTouchEvent does not have a valid unique_event_id, so we need to generate
one for MotionEventWeb.

[tdresser, 2015/04/20 20:12:09]

Shouldn't it have a valid unique_event_id?

[tdresser, 2015/04/20 20:26:20]

Lan pointed out that this isn't the case with synthesized events like touch
cancels.

   DCHECK_GT(GetPointerCount(), 0U);
 }
 
 MotionEventWeb::~MotionEventWeb() {}
 
-int MotionEventWeb::GetId() const {
-  return 0;
+uint64 MotionEventWeb::GetUniqueEventId() const {
+  return unique_event_id_;
 }
 
 MotionEventWeb::Action MotionEventWeb::GetAction() const {
   return cached_action_;
 }
 
 int MotionEventWeb::GetActionIndex() const {
   DCHECK(cached_action_ == ACTION_POINTER_UP ||
          cached_action_ == ACTION_POINTER_DOWN)
       << "Invalid action for GetActionIndex(): " << cached_action_;
@@ skipping 79 matching lines @@
 
 int MotionEventWeb::GetButtonState() const {
   return 0;
 }
 
 int MotionEventWeb::GetFlags() const {
   return WebEventModifiersToEventFlags(event_.modifiers);
 }
 
 }  // namespace content