Set the unique_event_id when converting from TouchEvent to WebTouchEvent

ui/events/test/motion_event_test_utils.h

 // 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.
 
 #ifndef UI_EVENTS_TEST_MOTION_EVENT_TEST_UTILS_H_
 #define UI_EVENTS_TEST_MOTION_EVENT_TEST_UTILS_H_
 
 #include <string>
 #include <vector>
 
@@ skipping 33 matching lines @@
   ~MockMotionEvent() override;
 
   // Utility methods.
   void PressPoint(float x, float y);
   void MovePoint(size_t index, float x, float y);
   void ReleasePoint();
   void CancelPoint();
   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);
   void ResolvePointers();
 };
 
 std::string ToString(const MotionEvent& event);
 
 }  // namespace test
 }  // namespace ui
 
 #endif  // UI_EVENTS_TEST_MOTION_EVENT_TEST_UTILS_H_