chrome: Cleanup class/struct forward declarations

chrome/browser/chromeos/file_system_provider/provided_file_system_observer.h

 // Copyright 2014 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_CHROMEOS_FILE_SYSTEM_PROVIDER_PROVIDED_FILE_SYSTEM_OBSERVER_H_
 #define CHROME_BROWSER_CHROMEOS_FILE_SYSTEM_PROVIDER_PROVIDED_FILE_SYSTEM_OBSERVER_H_
 
 #include <string>
 #include <vector>
 
 #include "base/callback.h"
 #include "base/files/file_path.h"
 #include "chrome/browser/chromeos/file_system_provider/watcher.h"
 #include "storage/browser/fileapi/watcher_manager.h"
 
 namespace chromeos {
 namespace file_system_provider {
 
 class ProvidedFileSystemInfo;
-class RequestManager;
 
 // Observer class to be notified about changes happened to the provided file
 // system, including watched entries.
 class ProvidedFileSystemObserver {
  public:
   struct Change;
 
   // Lust of changes.
   typedef std::vector<Change> Changes;
 
@@ skipping 24 matching lines @@
   // Called after the list of watchers is changed.
   virtual void OnWatcherListChanged(
       const ProvidedFileSystemInfo& file_system_info,
       const Watchers& watchers) = 0;
 };
 
 }  // namespace file_system_provider
 }  // namespace chromeos
 
 #endif  // CHROME_BROWSER_CHROMEOS_FILE_SYSTEM_PROVIDER_PROVIDED_FILE_SYSTEM_OBSERVER_H_