[SyncFS] Make MetadataDatabase operations synchronous

chrome/browser/sync_file_system/drive_backend/conflict_resolver_unittest.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/conflict_resolver.h"
 
 #include "base/bind.h"
 #include "base/callback.h"
 #include "base/files/file_util.h"
 #include "base/files/scoped_temp_dir.h"
@@ skipping 101 matching lines @@
 
   void DidInitializeMetadataDatabase(SyncEngineInitializer* initializer,
                                      SyncStatusCode* status_out,
                                      SyncStatusCode status) {
     context_->SetMetadataDatabase(initializer->PassMetadataDatabase());
     *status_out = status;
   }
 
   void RegisterApp(const std::string& app_id,
                    const std::string& app_root_folder_id) {
-    SyncStatusCode status = SYNC_STATUS_FAILED;
-    context_->GetMetadataDatabase()->RegisterApp(app_id, app_root_folder_id,
-                                                 CreateResultReceiver(&status));
-    base::RunLoop().RunUntilIdle();
+    SyncStatusCode status = context_->GetMetadataDatabase()->RegisterApp(
+        app_id, app_root_folder_id);
     EXPECT_EQ(SYNC_STATUS_OK, status);
   }
 
  protected:
   std::string CreateSyncRoot() {
     std::string sync_root_folder_id;
     EXPECT_EQ(google_apis::HTTP_CREATED,
               fake_drive_helper_->AddOrphanedFolder(
                   kSyncRootFolderTitle, &sync_root_folder_id));
     return sync_root_folder_id;
@@ skipping 384 matching lines @@
 
   EXPECT_EQ(4, CountParents(file));
 
   EXPECT_EQ(SYNC_STATUS_OK, RunConflictResolver());
 
   EXPECT_EQ(1, CountParents(file));
 }
 
 }  // namespace drive_backend
 }  // namespace sync_file_system