aura: Remove --aura-disable-hold-mouse-moves flag.

ui/aura/root_window.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 UI_AURA_ROOT_WINDOW_H_
 #define UI_AURA_ROOT_WINDOW_H_
 #pragma once
 
 #include <vector>
 
@@ skipping 381 matching lines @@
 
   bool synthesize_mouse_move_;
   bool waiting_on_compositing_end_;
   bool draw_on_compositing_end_;
 
   bool defer_draw_scheduling_;
 
   // How many holds are outstanding. We try to defer dispatching mouse moves
   // while the count is > 0.
   int mouse_move_hold_count_;
-  bool should_hold_mouse_moves_;
   scoped_ptr<MouseEvent> held_mouse_move_;
 
   CompositorLock* compositor_lock_;
   bool draw_on_compositor_unlock_;
 
   int draw_trace_count_;
 
   DISALLOW_COPY_AND_ASSIGN(RootWindow);
 };
 
 }  // namespace aura
 
 #endif  // UI_AURA_ROOT_WINDOW_H_