Set the unique_event_id when converting from TouchEvent to WebTouchEvent

ui/events/test/motion_event_test_utils.h

Index: ui/events/test/motion_event_test_utils.h
diff --git a/ui/events/test/motion_event_test_utils.h b/ui/events/test/motion_event_test_utils.h
index 4010bc465ef7d34dae74fb77521f0c0f44aba745..9b83fdc7a02f57a9d6995c6b6a3f80cd0c2f6b73 100644
--- a/ui/events/test/motion_event_test_utils.h
+++ b/ui/events/test/motion_event_test_utils.h
@@ -51,6 +51,7 @@ struct MockMotionEvent : public MotionEventGeneric {
   void SetTouchMajor(float new_touch_major);
   void SetRawOffset(float raw_offset_x, float raw_offset_y);
   void SetToolType(size_t index, ToolType tool_type);
+  void SetPrimaryPointerId(int id);
 
  private:
   void PushPointer(float x, float y);