gdata: Remove use of FindEntryByPathSync() fromMoveOnUIThread()

chrome/browser/chromeos/gdata/gdata_file_system_interface.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_INTERFACE_H_
 #define CHROME_BROWSER_CHROMEOS_GDATA_GDATA_FILE_SYSTEM_INTERFACE_H_
 
 #include <string>
 #include <vector>
 
@@ skipping 202 matching lines @@
   // This method also has the following assumptions/limitations that may be
   // relaxed or addressed later:
   // - |dest_file_path| must not exist.
   // - The parent of |dest_file_path| must already exist.
   //
   // The file entries represented by |src_file_path| and the parent directory
   // of |dest_file_path| need to be present in the in-memory representation
   // of the file system.
   //
   // Can be called from UI/IO thread. |callback| is run on the calling thread.
+  // |callback| must not be null.
   virtual void Move(const FilePath& src_file_path,
                     const FilePath& dest_file_path,
                     const FileOperationCallback& callback) = 0;
 
   // Removes |file_path| from the file system.  If |is_recursive| is set and
   // |file_path| represents a directory, we will also delete all of its
   // contained children elements. The file entry represented by |file_path|
   // needs to be present in in-memory representation of the file system that
   // in order to be removed.
   //
@@ skipping 119 matching lines @@
                                const FilePath& virtual_dir_path,
                                scoped_ptr<DocumentEntry> entry,
                                const FilePath& file_content_path,
                                GDataCache::FileOperationType cache_operation,
                                const base::Closure& callback) = 0;
 };
 
 }  // namespace gdata
 
 #endif  // CHROME_BROWSER_CHROMEOS_GDATA_GDATA_FILE_SYSTEM_INTERFACE_H_