drive: Remove FileCacheObserver::OnCacheCommitted

chrome/browser/chromeos/drive/file_cache_observer.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_CHROMEOS_DRIVE_FILE_CACHE_OBSERVER_H_
 #define CHROME_BROWSER_CHROMEOS_DRIVE_FILE_CACHE_OBSERVER_H_
 
 #include <string>
 
 namespace drive {
 namespace internal {
 
 // Interface for classes that need to observe events from FileCache.
 // All events are notified on UI thread.
 class FileCacheObserver {
  public:
   // Triggered when a file has been pinned successfully.
   virtual void OnCachePinned(const std::string& resource_id,
                              const std::string& md5) {}
 
   // Triggered when a file has been unpinned successfully.
   virtual void OnCacheUnpinned(const std::string& resource_id,
                                const std::string& md5) {}
 
-  // Triggered when a dirty file has been committed (saved) successfully.
-  virtual void OnCacheCommitted(const std::string& resource_id) {}
-
  protected:
   virtual ~FileCacheObserver() {}
 };
 
 }  // namespace internal
 }  // namespace drive
 
 #endif  // CHROME_BROWSER_CHROMEOS_DRIVE_FILE_CACHE_OBSERVER_H_