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

chrome/browser/sync_file_system/drive_backend/remote_to_local_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/remote_to_local_syncer.h"
 
 #include "base/bind.h"
 #include "base/callback.h"
 #include "base/file_util.h"
 #include "base/format_macros.h"
@@ skipping 671 matching lines @@
   remote_change_processor()->ApplyRemoteChange(
       FileChange(FileChange::FILE_CHANGE_DELETE, SYNC_FILE_TYPE_UNKNOWN),
       base::FilePath(),
       url_,
       callback);
 }
 
 void RemoteToLocalSyncer::DownloadFile(const SyncStatusCallback& callback) {
   DCHECK(sync_context_->GetWorkerTaskRunner()->RunsTasksOnCurrentThread());
 
-  base::Callback<void(webkit_blob::ScopedFile)> did_create_callback =
-      base::Bind(&RemoteToLocalSyncer::DidCreateTemporaryFileForDownload,
-                 weak_ptr_factory_.GetWeakPtr(), callback);
+  webkit_blob::ScopedFile file = CreateTemporaryFile(
+      make_scoped_refptr(sync_context_->GetWorkerTaskRunner()));
 
-  sync_context_->GetFileTaskRunner()->PostTask(
-      FROM_HERE,
-      CreateComposedFunction(
-          base::Bind(&CreateTemporaryFile,
-                     make_scoped_refptr(sync_context_->GetFileTaskRunner())),
-          RelayCallbackToTaskRunner(
-              sync_context_->GetWorkerTaskRunner(), FROM_HERE,
-              did_create_callback)));
-}
-
-void RemoteToLocalSyncer::DidCreateTemporaryFileForDownload(
-    const SyncStatusCallback& callback,
-    webkit_blob::ScopedFile file) {
-  DCHECK(sync_context_->GetWorkerTaskRunner()->RunsTasksOnCurrentThread());
   base::FilePath path = file.path();
   drive_service()->DownloadFile(
       path, remote_metadata_->file_id(),
       base::Bind(&RemoteToLocalSyncer::DidDownloadFile,
                  weak_ptr_factory_.GetWeakPtr(),
                  callback, base::Passed(&file)),
       google_apis::GetContentCallback(),
       google_apis::ProgressCallback());
 }
 
 void RemoteToLocalSyncer::DidDownloadFile(const SyncStatusCallback& callback,
                                           webkit_blob::ScopedFile file,
                                           google_apis::GDataErrorCode error,
                                           const base::FilePath&) {
   DCHECK(sync_context_->GetWorkerTaskRunner()->RunsTasksOnCurrentThread());
 
   SyncStatusCode status = GDataErrorCodeToSyncStatusCode(error);
   if (status != SYNC_STATUS_OK) {
     callback.Run(status);
     return;
   }
 
   base::FilePath path = file.path();
-  base::Callback<void(const std::string&)> did_calculate_callback =
-      base::Bind(&RemoteToLocalSyncer::DidCalculateMD5ForDownload,
-                 weak_ptr_factory_.GetWeakPtr(),
-                 callback, base::Passed(&file));
-
-  sync_context_->GetFileTaskRunner()->PostTask(
-      FROM_HERE,
-      CreateComposedFunction(
-          base::Bind(&drive::util::GetMd5Digest, path),
-          RelayCallbackToTaskRunner(
-              sync_context_->GetWorkerTaskRunner(), FROM_HERE,
-              did_calculate_callback)));
-}
-
-void RemoteToLocalSyncer::DidCalculateMD5ForDownload(
-    const SyncStatusCallback& callback,
-    webkit_blob::ScopedFile file,
-    const std::string& md5) {
+  const std::string md5 = drive::util::GetMd5Digest(path);
   if (md5.empty()) {
     callback.Run(SYNC_FILE_ERROR_NOT_FOUND);
     return;
   }
 
   if (md5 != remote_metadata_->details().md5()) {
     // File has been modified since last metadata retrieval.
 
     // Lower the priority of the tracker to prevent repeated remote sync to the
     // same tracker.
     metadata_database()->LowerTrackerPriority(dirty_tracker_->tracker_id());
     callback.Run(SYNC_STATUS_RETRY);
     return;
   }
 
-  base::FilePath path = file.path();
   remote_change_processor()->ApplyRemoteChange(
       FileChange(FileChange::FILE_CHANGE_ADD_OR_UPDATE, SYNC_FILE_TYPE_FILE),
       path, url_,
       base::Bind(&RemoteToLocalSyncer::DidApplyDownload,
                  weak_ptr_factory_.GetWeakPtr(),
                  callback, base::Passed(&file)));
 }
 
 void RemoteToLocalSyncer::DidApplyDownload(const SyncStatusCallback& callback,
                                            webkit_blob::ScopedFile,
@@ skipping 26 matching lines @@
 
 SyncStatusCallback RemoteToLocalSyncer::SyncCompletedCallback(
     scoped_ptr<SyncTaskToken> token) {
   return base::Bind(&RemoteToLocalSyncer::SyncCompleted,
                     weak_ptr_factory_.GetWeakPtr(),
                     base::Passed(&token));
 }
 
 }  // namespace drive_backend
 }  // namespace sync_file_system