gdata: Fix a bug where |root_| was accessed without a lock

chrome/browser/chromeos/gdata/gdata_file_system.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_GDATA_GDATA_FILE_SYSTEM_H_
 #define CHROME_BROWSER_CHROMEOS_GDATA_GDATA_FILE_SYSTEM_H_
 #pragma once
 
 #include <sys/stat.h>
 
@@ skipping 1196 matching lines @@
       const tracked_objects::Location& from_here,
       const base::Closure& task);
 
   // Similar to PostBlockingPoolSequencedTask() but this one takes a reply
   // callback that runs on the calling thread.
   void PostBlockingPoolSequencedTaskAndReply(
     const tracked_objects::Location& from_here,
     const base::Closure& request_task,
     const base::Closure& reply_task);
 
-  // Helper function used to perform file search on the calling thread of
-  // FindEntryByPath() request.
-  void FindEntryByPathOnCallingThread(const FilePath& search_file_path,
-                                      const FindEntryCallback& callback);
+  // Helper function used to perform synchronous file search on UI thread.
+  void FindEntryByPathSyncOnUIThread(const FilePath& search_file_path,
+                                     const FindEntryCallback& callback);
 
   void OnSetPinStateCompleted(const FileOperationCallback& callback,
                               base::PlatformFileError error,
                               const std::string& resource_id,
                               const std::string& md5);
 
   // Changes state of hosted documents visibility, triggers directory refresh.
   void SetHideHostedDocuments(bool hide);
 
   // Initializes preference change observer.
@@ skipping 114 matching lines @@
 };
 
 // Sets the free disk space getter for testing.
 // The existing getter is deleted.
 void SetFreeDiskSpaceGetterForTesting(
     FreeDiskSpaceGetterInterface* getter);
 
 }  // namespace gdata
 
 #endif  // CHROME_BROWSER_CHROMEOS_GDATA_GDATA_FILE_SYSTEM_H_