drive: Simplify TruncateOperation with ResourceEntry::local_id

chrome/browser/chromeos/drive/file_system/truncate_operation.h

 // Copyright 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 CHROME_BROWSER_CHROMEOS_DRIVE_FILE_SYSTEM_TRUNCATE_OPERATION_H_
 #define CHROME_BROWSER_CHROMEOS_DRIVE_FILE_SYSTEM_TRUNCATE_OPERATION_H_
 
 #include "base/basictypes.h"
 #include "base/memory/ref_counted.h"
 #include "base/memory/scoped_ptr.h"
@@ skipping 44 matching lines @@
   // Part of Truncate(). Called after EnsureFileDownloadedByPath() is complete.
   void TruncateAfterEnsureFileDownloadedByPath(
       int64 length,
       const FileOperationCallback& callback,
       FileError error,
       const base::FilePath& local_file_path,
       scoped_ptr<ResourceEntry> resource_entry);
 
   // Part of Truncate(). Called after TruncateOnBlockingPool() is complete.
   void TruncateAfterTruncateOnBlockingPool(
-      const std::string* local_id,
+      const std::string& local_id,
       const FileOperationCallback& callback,
       FileError error);
 
   scoped_refptr<base::SequencedTaskRunner> blocking_task_runner_;
   OperationObserver* observer_;
   internal::ResourceMetadata* metadata_;
   internal::FileCache* cache_;
 
   scoped_ptr<DownloadOperation> download_operation_;
 
   // Note: This should remain the last member so it'll be destroyed and
   // invalidate the weak pointers before any other members are destroyed.
   base::WeakPtrFactory<TruncateOperation> weak_ptr_factory_;
   DISALLOW_COPY_AND_ASSIGN(TruncateOperation);
 };
 
 }  // namespace file_system
 }  // namespace drive
 
 #endif  // CHROME_BROWSER_CHROMEOS_DRIVE_FILE_SYSTEM_TRUNCATE_OPERATION_H_