Set the unique_event_id when converting from TouchEvent to WebTouchEvent

ui/events/gesture_detection/motion_event_generic.cc

Index: ui/events/gesture_detection/motion_event_generic.cc
diff --git a/ui/events/gesture_detection/motion_event_generic.cc b/ui/events/gesture_detection/motion_event_generic.cc
index 475e9c5bc808eb3d40f042fd5a8aff751a4858c5..59f4c2b498b23346606f5c3c5c9e1e308fdaa079 100644
--- a/ui/events/gesture_detection/motion_event_generic.cc
+++ b/ui/events/gesture_detection/motion_event_generic.cc
@@ -5,6 +5,7 @@
 #include "ui/events/gesture_detection/motion_event_generic.h"
 
 #include "base/logging.h"
+#include "ui/events/base_event_utils.h"
 
 namespace ui {
 
@@ -46,7 +47,7 @@ MotionEventGeneric::MotionEventGeneric(Action action,
                                        const PointerProperties& pointer)
     : action_(action),
       event_time_(event_time),
-      id_(0),
+      unique_event_id_(ui::GetNextTouchEventId()),
       action_index_(0),
       button_state_(0),
       flags_(0) {
@@ -56,7 +57,7 @@ MotionEventGeneric::MotionEventGeneric(Action action,
 MotionEventGeneric::MotionEventGeneric(const MotionEventGeneric& other)
     : action_(other.action_),
       event_time_(other.event_time_),
-      id_(other.id_),
+      unique_event_id_(other.unique_event_id_),
       action_index_(other.action_index_),
       button_state_(other.button_state_),
       flags_(other.flags_),
@@ -69,8 +70,8 @@ MotionEventGeneric::MotionEventGeneric(const MotionEventGeneric& other)
 MotionEventGeneric::~MotionEventGeneric() {
 }
 
-int MotionEventGeneric::GetId() const {
-  return id_;
+uint64 MotionEventGeneric::GetUniqueEventId() const {
+  return unique_event_id_;
 }
 
 MotionEvent::Action MotionEventGeneric::GetAction() const {
@@ -219,14 +220,17 @@ void MotionEventGeneric::PushHistoricalEvent(scoped_ptr<MotionEvent> event) {
 }
 
 MotionEventGeneric::MotionEventGeneric()
-    : action_(ACTION_CANCEL), id_(0), action_index_(0), button_state_(0) {
+    : action_(ACTION_CANCEL),
+      unique_event_id_(ui::GetNextTouchEventId()),

[jdduke (slow), 2015/04/21 22:40:16]

I can't say I love using globals, but this is probably the simplest thing to do
I guess.

[tdresser, 2015/04/22 12:59:00]

I agree, but I think that ensuring that these ids are unique across all forms of
input is worth it. I'm worries about cases where, for example, you're touching
the screen and using touch emulation at the same time, and you end up with
collisions.

[lanwei, 2015/04/22 20:51:31]

I also agree, in many cases such as for different platforms it does not matter
if they have same unique_event_id, but it is better to keep this way Tim gave an
good example.

+      action_index_(0),
+      button_state_(0) {
 }
 
 MotionEventGeneric::MotionEventGeneric(const MotionEvent& event,
                                        bool with_history)
     : action_(event.GetAction()),
       event_time_(event.GetEventTime()),
-      id_(event.GetId()),
+      unique_event_id_(event.GetUniqueEventId()),
       action_index_(
           (action_ == ACTION_POINTER_UP || action_ == ACTION_POINTER_DOWN)
               ? event.GetActionIndex()
@@ -259,7 +263,7 @@ MotionEventGeneric& MotionEventGeneric::operator=(
     const MotionEventGeneric& other) {
   action_ = other.action_;
   event_time_ = other.event_time_;
-  id_ = other.id_;
+  unique_event_id_ = other.unique_event_id_;
   action_index_ = other.action_index_;
   button_state_ = other.button_state_;
   flags_ = other.flags_;