Remove obviously unneeded forward declarations in chrome/browser/[abef]*/*.h.

chrome/browser/extensions/user_script_master.h

-// Copyright (c) 2008 The Chromium Authors. All rights reserved.
+// Copyright (c) 2010 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_USER_SCRIPT_MASTER_H_
 #define CHROME_BROWSER_EXTENSIONS_USER_SCRIPT_MASTER_H_
 #pragma once
 
 #include "base/file_path.h"
 #include "base/gtest_prod_util.h"
 #include "base/scoped_ptr.h"
 #include "base/shared_memory.h"
 #include "chrome/browser/chrome_thread.h"
 #include "chrome/common/extensions/user_script.h"
 #include "chrome/common/notification_registrar.h"
 
 namespace base {
 class StringPiece;
 }
 
-class Extension;
 class Profile;
 
 // Manages a segment of shared memory that contains the user scripts the user
 // has installed.  Lives on the UI thread.
 class UserScriptMaster : public base::RefCountedThreadSafe<UserScriptMaster>,
                          public NotificationObserver {
  public:
   // For testability, the constructor takes the path the scripts live in.
   // This is normally a directory inside the profile.
   explicit UserScriptMaster(const FilePath& script_dir, Profile* profile);
@@ skipping 121 matching lines @@
   // finishes.  This boolean tracks whether another scan is pending.
   bool pending_scan_;
 
   // The profile for which the scripts managed here are installed.
   Profile* profile_;
 
   DISALLOW_COPY_AND_ASSIGN(UserScriptMaster);
 };
 
 #endif  // CHROME_BROWSER_EXTENSIONS_USER_SCRIPT_MASTER_H_