drive: Stop using FileCacheEntry related methods in FileCache

chrome/browser/chromeos/drive/file_cache.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_H_
 #define CHROME_BROWSER_CHROMEOS_DRIVE_FILE_CACHE_H_
 
 #include <set>
 #include <string>
 
@@ skipping 96 matching lines @@
 
   // Calculates MD5 of the cache file and updates the stored value.
   FileError UpdateMd5(const std::string& id);
 
   // Clears dirty state of the specified entry.
   FileError ClearDirty(const std::string& id);
 
   // Removes the specified cache entry and delete cache files if available.
   FileError Remove(const std::string& id);
 
-  // Removes all the files in the cache directory and cache entries in DB.
+  // Removes all the files in the cache directory.
   bool ClearAll();
 
   // Initializes the cache. Returns true on success.
   bool Initialize();
 
   // Destroys this cache. This function posts a task to the blocking task
   // runner to safely delete the object.
   // Must be called on the UI thread.
   void Destroy();
 
@@ skipping 53 matching lines @@
   // invalidate its weak pointers before any other members are destroyed.
   // This object should be accessed only on |blocking_task_runner_|.
   base::WeakPtrFactory<FileCache> weak_ptr_factory_;
   DISALLOW_COPY_AND_ASSIGN(FileCache);
 };
 
 }  // namespace internal
 }  // namespace drive
 
 #endif  // CHROME_BROWSER_CHROMEOS_DRIVE_FILE_CACHE_H_