Reverting this CL because it was committed before I gave the final LGTM.

chrome/browser/chromeos/accessibility/magnification_manager.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 CHROME_BROWSER_CHROMEOS_ACCESSIBILITY_MAGNIFICATION_MANAGER_H_
-#define CHROME_BROWSER_CHROMEOS_ACCESSIBILITY_MAGNIFICATION_MANAGER_H_
-
-namespace chromeos {
-
-
-// MagnificationManager controls the full screen magnifier from chrome-browser
-// side (not ash side).
-//
-// MagnificationManager does:
-//   - Watch logged-in. Changes the behavior between the login screen and user
-//     desktop.
-//   - Watch change of the pref. When the pref changes, the setting of the
-//     magnifier will interlock with it.
-
-class MagnificationManager {
- public:
-  // Creates an instance of MagnificationManager. This should be called once,
-  // because only one instance should exist at the same time.
-  static MagnificationManager* CreateInstance();
-  // Returns the existing instance. If there is no instance, returns NULL.
-  static MagnificationManager* GetInstance();
-
-  virtual ~MagnificationManager() {}
-
-  // Returns if the magnifier is enabled or not.
-  virtual bool IsEnabled() = 0;
-  // Enables (or disables if |enabled| is false) the magnifierh.
-  virtual void SetEnabled(bool enabled) = 0;
-};
-
-}  // namespace chromeos
-
-#endif  // CHROME_BROWSER_CHROMEOS_ACCESSIBILITY_MAGNIFICATION_MANAGER_H_