Remove const from int return type on aura::Env::mouse_button_flags()

ui/aura/env.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_ENV_H_
 #define UI_AURA_ENV_H_
 
 #include "base/memory/scoped_ptr.h"
 #include "base/observer_list.h"
 #include "base/supports_user_data.h"
@@ skipping 24 matching lines @@
   // |create_event_source| is true a PlatformEventSource is created.
   // TODO(sky): nuke |create_event_source|. Only necessary while mojo's
   // nativeviewportservice lives in the same process as the viewmanager.
   static void CreateInstance(bool create_event_source);
   static Env* GetInstance();
   static void DeleteInstance();
 
   void AddObserver(EnvObserver* observer);
   void RemoveObserver(EnvObserver* observer);
 
-  const int mouse_button_flags() const { return mouse_button_flags_; }
+  int mouse_button_flags() const { return mouse_button_flags_; }
   void set_mouse_button_flags(int mouse_button_flags) {
     mouse_button_flags_ = mouse_button_flags;
   }
   // Returns true if a mouse button is down. This may query the native OS,
   // otherwise it uses |mouse_button_flags_|.
   bool IsMouseButtonDown() const;
 
   // Gets/sets the last mouse location seen in a mouse event in the screen
   // coordinates.
   const gfx::Point& last_mouse_location() const { return last_mouse_location_; }
@@ skipping 47 matching lines @@
   scoped_ptr<ui::PlatformEventSource> event_source_;
 
   ui::ContextFactory* context_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(Env);
 };
 
 }  // namespace aura
 
 #endif  // UI_AURA_ENV_H_