[SyncFS] Remove usage of file task runner under drive_backend/

chrome/browser/sync_file_system/drive_backend/local_to_remote_syncer.cc

 // Copyright 2013 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/sync_file_system/drive_backend/local_to_remote_syncer.h"
 
 #include <string>
 #include <vector>
 
 #include "base/callback.h"
@@ skipping 480 matching lines @@
   }
 
   SyncCompleted(token.Pass(), SYNC_STATUS_OK);
 }
 
 void LocalToRemoteSyncer::UploadExistingFile(scoped_ptr<SyncTaskToken> token) {
   DCHECK(remote_file_tracker_);
   DCHECK(remote_file_tracker_->has_synced_details());
   DCHECK(sync_context_->GetWorkerTaskRunner()->RunsTasksOnCurrentThread());
 
-  base::Callback<void(const std::string&)> did_calculate_callback =
-      base::Bind(&LocalToRemoteSyncer::DidGetMD5ForUpload,
-                 weak_ptr_factory_.GetWeakPtr(), base::Passed(&token));
-
-  sync_context_->GetFileTaskRunner()->PostTask(
-      FROM_HERE,
-      CreateComposedFunction(
-          base::Bind(&drive::util::GetMd5Digest, local_path_),
-          RelayCallbackToTaskRunner(
-              sync_context_->GetWorkerTaskRunner(), FROM_HERE,
-              did_calculate_callback)));
-}
-
-void LocalToRemoteSyncer::DidGetMD5ForUpload(
-    scoped_ptr<SyncTaskToken> token,
-    const std::string& local_file_md5) {
+  const std::string local_file_md5 = drive::util::GetMd5Digest(local_path_);
   if (local_file_md5 == remote_file_tracker_->synced_details().md5()) {
     // Local file is not changed.
     SyncCompleted(token.Pass(), SYNC_STATUS_OK);
     return;
   }
 
   sync_action_ = SYNC_ACTION_UPDATED;
 
   drive::DriveUploader::UploadExistingFileOptions options;
   options.etag = remote_file_tracker_->synced_details().etag();
@@ skipping 261 matching lines @@
   set_used_network(true);
   return sync_context_->GetDriveUploader();
 }
 
 MetadataDatabase* LocalToRemoteSyncer::metadata_database() {
   return sync_context_->GetMetadataDatabase();
 }
 
 }  // namespace drive_backend
 }  // namespace sync_file_system