extensions: Cleanup class/struct fwd declarations

extensions/browser/app_sorting.h

 // Copyright (c) 2013 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 EXTENSIONS_BROWSER_APP_SORTING_H_
 #define EXTENSIONS_BROWSER_APP_SORTING_H_
 
 #include <stddef.h>
 
 #include <string>
 
 #include "base/macros.h"
 #include "components/sync/model/string_ordinal.h"
 #include "extensions/common/extension.h"
 
 namespace extensions {
 
-class ExtensionScopedPrefs;
-
 // An interface that provides a fixed ordering for a set of apps.
 class AppSorting {
  public:
   AppSorting() {}
   virtual ~AppSorting() {}
 
   // Resolves any conflicts the might be created as a result of syncing that
   // results in two icons having the same page and app launch ordinal. After
   // this is called it is guaranteed that there are no collisions of NTP icons.
   virtual void FixNTPOrdinalCollisions() = 0;
@@ skipping 81 matching lines @@
   virtual void SetExtensionVisible(const std::string& extension_id,
                                    bool visible) = 0;
 
  private:
   DISALLOW_COPY_AND_ASSIGN(AppSorting);
 };
 
 }  // namespace extensions
 
 #endif  // EXTENSIONS_BROWSER_APP_SORTING_H_