Cleanup: Remove unneeded forward declarations in chrome/installer.

chrome/installer/util/chrome_frame_distribution.h

 // Copyright (c) 2011 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.
 //
 // This file extends the browser distribution with a specific implementation
 // for Chrome Frame.
 
 #ifndef CHROME_INSTALLER_UTIL_CHROME_FRAME_DISTRIBUTION_H_
 #define CHROME_INSTALLER_UTIL_CHROME_FRAME_DISTRIBUTION_H_
 #pragma once
 
 #include <string>
 #include <vector>
 
 #include "chrome/installer/util/browser_distribution.h"
 #include "chrome/installer/util/util_constants.h"
 
-namespace installer {
-class MasterPreferences;
-}
-
 class ChromeFrameDistribution : public BrowserDistribution {
  public:
   virtual std::wstring GetAppGuid() OVERRIDE;
 
   virtual std::wstring GetApplicationName() OVERRIDE;
 
   virtual std::wstring GetAppShortCutName() OVERRIDE;
 
   virtual std::wstring GetAlternateApplicationName() OVERRIDE;
 
@@ skipping 28 matching lines @@
       installer::InstallStatus install_status) OVERRIDE;
 
  protected:
   friend class BrowserDistribution;
 
   // Disallow construction from non-friends.
   ChromeFrameDistribution();
 };
 
 #endif  // CHROME_INSTALLER_UTIL_CHROME_FRAME_DISTRIBUTION_H_