Cleanup: Remove some unneeded Extension* class forward declarations.

chrome/browser/extensions/extension_error_ui_default.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_EXTENSIONS_EXTENSION_ERROR_UI_DEFAULT_H_
 #define CHROME_BROWSER_EXTENSIONS_EXTENSION_ERROR_UI_DEFAULT_H_
 
 #include "base/basictypes.h"
 #include "base/compiler_specific.h"
 #include "chrome/browser/extensions/extension_error_ui.h"
 #include "chrome/browser/ui/global_error/global_error.h"
 #include "extensions/common/extension.h"
 
 class Browser;
-class ExtensionService;
 class Profile;
 
 namespace extensions {
 
 class ExtensionErrorUIDefault : public ExtensionErrorUI {
  public:
   explicit ExtensionErrorUIDefault(ExtensionErrorUI::Delegate* delegate);
   virtual ~ExtensionErrorUIDefault();
 
   // ExtensionErrorUI implementation:
@@ skipping 33 matching lines @@
   Browser* browser_;
 
   scoped_ptr<ExtensionGlobalError> global_error_;
 
   DISALLOW_COPY_AND_ASSIGN(ExtensionErrorUIDefault);
 };
 
 }  // namespace extensions
 
 #endif  // CHROME_BROWSER_EXTENSIONS_EXTENSION_ERROR_UI_DEFAULT_H_