Set the unique_event_id when converting from TouchEvent to WebTouchEvent

ui/events/gesture_detection/motion_event_generic.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 "ui/events/gesture_detection/motion_event_generic.h"
 
 #include "base/logging.h"
 
 namespace ui {
 
@@ skipping 28 matching lines @@
       touch_minor(event.GetTouchMinor(pointer_index)),
       orientation(event.GetOrientation(pointer_index)),
       source_device_id(0) {
 }
 
 MotionEventGeneric::MotionEventGeneric(Action action,
                                        base::TimeTicks event_time,
                                        const PointerProperties& pointer)
     : action_(action),
       event_time_(event_time),
-      id_(0),
       action_index_(0),

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

unique_event_id_ needs to be initialized in all of these constructors

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

The MotionEventGeneric's unique_event_id is from TouchEvent, so we do not
generate it in its constructor.

[jdduke (slow), 2015/04/21 14:56:50]

I don't fully understand this comment, what do you mean it's from TouchEvent?
Even if we don't create a new ID here, don't we have to initialize the member
variable to 0?

[lanwei, 2015/04/21 21:32:45]

Sorry, I was wrong, I thought we do not pass MotionEventGeneric objects to the
CreateWebTouchEventFromMotionEvent function, so we do not care if it has a
unique_event_id value. We should initialize the unique_event_id in all the
constructors. 

       button_state_(0),
       flags_(0) {
   PushPointer(pointer);
 }
 
 MotionEventGeneric::MotionEventGeneric(const MotionEventGeneric& other)
     : action_(other.action_),
       event_time_(other.event_time_),
-      id_(other.id_),
       action_index_(other.action_index_),
       button_state_(other.button_state_),
       flags_(other.flags_),
       pointers_(other.pointers_) {
   const size_t history_size = other.GetHistorySize();
   for (size_t h = 0; h < history_size; ++h)
     PushHistoricalEvent(other.historical_events_[h]->Clone());
 }
 
 MotionEventGeneric::~MotionEventGeneric() {
 }
 
-int MotionEventGeneric::GetId() const {
-  return id_;
+uint64 MotionEventGeneric::GetUniqueEventId() const {
+  return unique_event_id_;
 }
 
 MotionEvent::Action MotionEventGeneric::GetAction() const {
   return action_;
 }
 
 int MotionEventGeneric::GetActionIndex() const {
   DCHECK(action_ == ACTION_POINTER_DOWN || action_ == ACTION_POINTER_UP);
   DCHECK_GE(action_index_, 0);
   DCHECK_LT(action_index_, static_cast<int>(pointers_->size()));
@@ skipping 128 matching lines @@
   DCHECK(event);
   DCHECK_EQ(event->GetAction(), ACTION_MOVE);
   DCHECK_EQ(event->GetPointerCount(), GetPointerCount());
   DCHECK_EQ(event->GetAction(), GetAction());
   DCHECK_LE(event->GetEventTime().ToInternalValue(),
             GetEventTime().ToInternalValue());
   historical_events_.push_back(event.release());
 }
 
 MotionEventGeneric::MotionEventGeneric()
-    : action_(ACTION_CANCEL), id_(0), action_index_(0), button_state_(0) {
+    : action_(ACTION_CANCEL), action_index_(0), button_state_(0) {
 }
 
 MotionEventGeneric::MotionEventGeneric(const MotionEvent& event,
                                        bool with_history)
     : action_(event.GetAction()),
       event_time_(event.GetEventTime()),
-      id_(event.GetId()),
       action_index_(
           (action_ == ACTION_POINTER_UP || action_ == ACTION_POINTER_DOWN)
               ? event.GetActionIndex()
               : 0),
       button_state_(event.GetButtonState()),
       flags_(event.GetFlags()) {
   const size_t pointer_count = event.GetPointerCount();
   for (size_t i = 0; i < pointer_count; ++i)
     PushPointer(PointerProperties(event, i));
 
@@ skipping 12 matching lines @@
                             event.GetHistoricalTouchMajor(i, h)));
     }
     PushHistoricalEvent(historical_event.Pass());
   }
 }
 
 MotionEventGeneric& MotionEventGeneric::operator=(
     const MotionEventGeneric& other) {
   action_ = other.action_;
   event_time_ = other.event_time_;
-  id_ = other.id_;
   action_index_ = other.action_index_;

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

Don't we need to copy the unique_event_id_?

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

Done.

   button_state_ = other.button_state_;
   flags_ = other.flags_;
   pointers_ = other.pointers_;
   const size_t history_size = other.GetHistorySize();
   for (size_t h = 0; h < history_size; ++h)
     PushHistoricalEvent(other.historical_events_[h]->Clone());
   return *this;
 }
 
 void MotionEventGeneric::PopPointer() {
   DCHECK_GT(pointers_->size(), 0U);
   pointers_->pop_back();
 }
 
 }  // namespace ui