gdata: Make GDataFileSystem::ReadDirectoryByPath() much more efficient

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 44 matching lines @@
                             scoped_ptr<GDataEntryProto> file_proto)>
     GetEntryInfoWithFilePathCallback;
 
 // Used to get entry info from the file system.
 // If |error| is not PLATFORM_FILE_OK, |entry_info| is set to NULL.
 typedef base::Callback<void(GDataFileError error,
                             scoped_ptr<GDataEntryProto> entry_proto)>
     GetEntryInfoCallback;
 
 // Used to read a directory from the file system.
-// If |error| is not PLATFORM_FILE_OK, |directory_info| is set to NULL.
+// If |error| is not PLATFORM_FILE_OK, |entries| is set to NULL.
+// |entries| are contents, both files and directories, of the directory.
+typedef std::vector<GDataEntryProto> GDataEntryProtoVector;
 typedef base::Callback<void(GDataFileError error,
                             bool hide_hosted_documents,
-                            scoped_ptr<GDataDirectoryProto> directory_proto)>
+                            scoped_ptr<GDataEntryProtoVector> entries)>
     ReadDirectoryCallback;
 
 // Used to get drive content search results.
 // If |error| is not PLATFORM_FILE_OK, |result_paths| is empty.
 typedef base::Callback<void(
     GDataFileError error,
     scoped_ptr<std::vector<SearchResultInfo> > result_paths)> SearchCallback;
 
 // Used to open files from the file system. |file_path| is the path on the local
 // file system for the opened file.
@@ skipping 264 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_