Set the unique_event_id when converting from TouchEvent to WebTouchEvent

content/browser/renderer_host/input/motion_event_web.h

Index: content/browser/renderer_host/input/motion_event_web.h
diff --git a/content/browser/renderer_host/input/motion_event_web.h b/content/browser/renderer_host/input/motion_event_web.h
index f3d85abfc123b4a70fc89e211a240bc1e27b4aa3..ed253978c70a65f734264ada9cbf40d14a020dfe 100644
--- a/content/browser/renderer_host/input/motion_event_web.h
+++ b/content/browser/renderer_host/input/motion_event_web.h
@@ -18,6 +18,7 @@ class MotionEventWeb : public ui::MotionEvent {
 
   // ui::MotionEvent
   int GetId() const override;
+  uint64 GetUniqueEventId() const override;
   Action GetAction() const override;
   int GetActionIndex() const override;
   size_t GetPointerCount() const override;
@@ -39,6 +40,7 @@ class MotionEventWeb : public ui::MotionEvent {
   blink::WebTouchEvent event_;
   Action cached_action_;
   int cached_action_index_;
+  const uint64 unique_event_id_;
 
   DISALLOW_COPY_AND_ASSIGN(MotionEventWeb);
 };