Make largest_changestamp setter/getter asynchronous.

chrome/browser/chromeos/drive/drive_file_system.cc

 // 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.
 
 #include "chrome/browser/chromeos/drive/drive_file_system.h"
 
 #include "base/bind.h"
 #include "base/file_util.h"
 #include "base/json/json_file_value_serializer.h"
 #include "base/message_loop_proxy.h"
@@ skipping 135 matching lines @@
 // create GetEntryInfoCallback.
 void RunGetEntryInfoWithFilePathCallback(
     const GetEntryInfoWithFilePathCallback& callback,
     const FilePath& path,
     DriveFileError error,
     scoped_ptr<DriveEntryProto> entry_proto) {
   DCHECK(!callback.is_null());
   callback.Run(error, path, entry_proto.Pass());
 }
 
+// Callback for DriveResourceMetadata::GetLargestChangestamp.
+// |callback| must not be null.
+void OnGetLargestChangestamp(DriveFileSystemMetadata metadata,

[satorux1, 2013/01/15 19:19:01]

Maybe: const DriveFileSystemMetadata& metadata

[achuithb, 2013/01/15 22:10:36]

How strongly do you feel about this? I need to modify metadata below, so I'd
need to make another temporary if this param is const.

[satorux1, 2013/01/16 00:47:30]

Ah then this is fine. Maybe:

DriveFileSystemMetadata metadata,  // will be modifed

[achuithb, 2013/01/16 01:00:22]

Done.

+                             const GetFilesystemMetadataCallback& callback,
+                             int64 largest_changestamp) {
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
+  DCHECK(!callback.is_null());
+
+  metadata.largest_changestamp = largest_changestamp;
+  callback.Run(metadata);
+}
+
 }  // namespace
 
 // DriveFileSystem::FindFirstMissingParentDirectoryParams implementation.
 struct DriveFileSystem::FindFirstMissingParentDirectoryParams {
   FindFirstMissingParentDirectoryParams(
       const std::vector<FilePath::StringType>& path_parts,
       const FindFirstMissingParentDirectoryCallback& callback)
       : path_parts(path_parts),
         index(0),
         callback(callback) {
@@ skipping 1608 matching lines @@
 
   OnDirectoryChanged(file_path.DirName());
 
   cache_->Store(params.resource_id,
                 params.md5,
                 params.file_content_path,
                 DriveCache::FILE_OPERATION_COPY,
                 params.callback);
 }
 
-DriveFileSystemMetadata DriveFileSystem::GetMetadata() const {
+void DriveFileSystem::GetMetadata(
+    const GetFilesystemMetadataCallback& callback) {
+  DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
+  DCHECK(!callback.is_null());
+
   DriveFileSystemMetadata metadata;
-  metadata.largest_changestamp = resource_metadata_->largest_changestamp();
   metadata.loaded = resource_metadata_->loaded();
   metadata.refreshing = feed_loader_->refreshing();
 
   // Metadata related to delta update.
   metadata.push_notification_enabled = push_notification_enabled_;
   metadata.polling_interval_sec = polling_interval_sec_;
   metadata.last_update_check_time = last_update_check_time_;
   metadata.last_update_check_error = last_update_check_error_;
 
-  return metadata;
+  resource_metadata_->GetLargestChangestamp(
+      base::Bind(&OnGetLargestChangestamp, metadata, callback));
 }
 
 void DriveFileSystem::OnDisableDriveHostedFilesChanged() {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
   PrefService* pref_service = profile_->GetPrefs();
   SetHideHostedDocuments(
       pref_service->GetBoolean(prefs::kDisableDriveHostedFiles));
 }
 
 void DriveFileSystem::SetHideHostedDocuments(bool hide) {
@@ skipping 334 matching lines @@
     return;
   }
 
   PlatformFileInfoProto entry_file_info;
   util::ConvertPlatformFileInfoToProto(*file_info, &entry_file_info);
   *entry_proto->mutable_file_info() = entry_file_info;
   callback.Run(DRIVE_FILE_OK, entry_proto.Pass());
 }
 
 }  // namespace drive