Make the second click on the app shelf icon close the window-list bubble.

ash/shelf/shelf_view.h

 // Copyright (c) 2012 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 ASH_SHELF_SHELF_VIEW_H_
 #define ASH_SHELF_SHELF_VIEW_H_
 
 #include <utility>
 #include <vector>
 
@@ skipping 417 matching lines @@
 
   // True when this ShelfView is used for Overflow Bubble.
   bool overflow_mode_;
 
   // Holds a pointer to main ShelfView when a ShelfView is in overflow mode.
   ShelfView* main_shelf_;
 
   // True when ripped item from overflow bubble is entered into Shelf.
   bool dragged_off_from_overflow_to_shelf_;
 
+  // Record the position of each pointer down event.
+  gfx::Point pointer_pressed_position_;
+
+  // True if the pointer press position is the same with the previous one.
+  bool pressed_on_same_position_;
+
   DISALLOW_COPY_AND_ASSIGN(ShelfView);
 };
 
 }  // namespace ash
 
 #endif  // ASH_SHELF_SHELF_VIEW_H_