Cleanup: Remove unneeded forward declarations from various chrome subdirectories.

chrome/common/extensions/extension_permission_set.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.
 
 #ifndef CHROME_COMMON_EXTENSIONS_EXTENSION_PERMISSION_SET_H_
 #define CHROME_COMMON_EXTENSIONS_EXTENSION_PERMISSION_SET_H_
 #pragma once
 
 #include <map>
 #include <set>
 #include <string>
 #include <vector>
 
 #include "base/gtest_prod_util.h"
 #include "base/memory/ref_counted.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/memory/singleton.h"
 #include "base/string16.h"
 #include "chrome/common/extensions/url_pattern_set.h"
 
 class Extension;
-class ExtensionPrefs;
 
 // When prompting the user to install or approve permissions, we display
 // messages describing the effects of the permissions rather than listing the
 // permissions themselves. Each ExtensionPermissionMessage represents one of the
 // messages shown to the user.
 class ExtensionPermissionMessage {
  public:
   // Do not reorder this enumeration. If you need to add a new enum, add it just
   // prior to kEnumBoundary.
   enum ID {
@@ skipping 382 matching lines @@
 
   // The list of hosts that can be scripted by content scripts.
   // TODO(jstritar): Rename to "user_script_hosts_"?
   URLPatternSet scriptable_hosts_;
 
   // The list of hosts this effectively grants access to.
   URLPatternSet effective_hosts_;
 };
 
 #endif  // CHROME_COMMON_EXTENSIONS_EXTENSION_PERMISSION_SET_H_