Remove root resource id aliasing from DriveResourceMetadata.

chrome/browser/chromeos/drive/drive_resource_metadata.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_DRIVE_RESOURCE_METADATA_H_
 #define CHROME_BROWSER_CHROMEOS_DRIVE_DRIVE_RESOURCE_METADATA_H_
 
 #include <map>
 #include <set>
 #include <string>
@@ skipping 116 matching lines @@
 
 // Used to receive the result from GetEntryInfoPairCallback().
 typedef base::Callback<void(scoped_ptr<EntryInfoPairResult> pair_result)>
     GetEntryInfoPairCallback;
 
 // Storage for Drive Metadata.
 class DriveResourceMetadata {
  public:
   // |root_resource_id| is the resource id for the root directory.
   DriveResourceMetadata(
-      const std::string& root_resource_id,
       const base::FilePath& data_directory_path,
       scoped_refptr<base::SequencedTaskRunner> blocking_task_runner);
 
   // Initializes this object.
   // This method should be called before any other methods.
   void Initialize(const FileOperationCallback& callback);
 
   // Destroys this object.  This method posts a task to |blocking_task_runner_|
   // to safely delete this object.
   void Destroy();
@@ skipping 238 matching lines @@
 
   // Parses metadata from string and set up directory structure.
   bool ParseFromString(const std::string& serialized_proto);
 
   const base::FilePath data_directory_path_;
 
   scoped_refptr<base::SequencedTaskRunner> blocking_task_runner_;
 
   scoped_ptr<DriveResourceMetadataStorage> storage_;
 
-  std::string root_resource_id_;
-
   base::Time last_serialized_;
   size_t serialized_size_;
 
   // This should remain the last member so it'll be destroyed first and
   // invalidate its weak pointers before other members are destroyed.
   base::WeakPtrFactory<DriveResourceMetadata> weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(DriveResourceMetadata);
 };
 
 }  // namespace drive
 
 #endif  // CHROME_BROWSER_CHROMEOS_DRIVE_DRIVE_RESOURCE_METADATA_H_