Set the unique_event_id when converting from TouchEvent to WebTouchEvent

ui/events/gesture_detection/motion_event_generic.h

Index: ui/events/gesture_detection/motion_event_generic.h
diff --git a/ui/events/gesture_detection/motion_event_generic.h b/ui/events/gesture_detection/motion_event_generic.h
index 9d7733fafd1a0d5d57aa42a6d7af14bc276ddd57..2adea657f80b8d3431017b31db5874ccfaa6285a 100644
--- a/ui/events/gesture_detection/motion_event_generic.h
+++ b/ui/events/gesture_detection/motion_event_generic.h
@@ -44,6 +44,7 @@ class GESTURE_DETECTION_EXPORT MotionEventGeneric : public MotionEvent {
 
   // MotionEvent implementation.
   int GetId() const override;
+  uint64 GetUniqueId() const override;
   Action GetAction() const override;
   int GetActionIndex() const override;
   size_t GetPointerCount() const override;
@@ -79,6 +80,7 @@ class GESTURE_DETECTION_EXPORT MotionEventGeneric : public MotionEvent {
   void set_action(Action action) { action_ = action; }
   void set_event_time(base::TimeTicks event_time) { event_time_ = event_time; }
   void set_id(int id) { id_ = id; }
+  void set_unique_id(uint64 unique_id) { unique_id_ = unique_id; }
   void set_action_index(int action_index) { action_index_ = action_index; }
   void set_button_state(int button_state) { button_state_ = button_state; }
   void set_flags(int flags) { flags_ = flags; }
@@ -104,6 +106,7 @@ class GESTURE_DETECTION_EXPORT MotionEventGeneric : public MotionEvent {
   Action action_;
   base::TimeTicks event_time_;
   int id_;
+  uint64 unique_id_;
   int action_index_;
   int button_state_;
   int flags_;