[SyncFS] Make SyncEngineInitializer run as a background task (3/3)

chrome/browser/sync_file_system/drive_backend/local_to_remote_syncer_unittest.cc

Index: chrome/browser/sync_file_system/drive_backend/local_to_remote_syncer_unittest.cc
diff --git a/chrome/browser/sync_file_system/drive_backend/local_to_remote_syncer_unittest.cc b/chrome/browser/sync_file_system/drive_backend/local_to_remote_syncer_unittest.cc
index f5a1d5321ea4a9ad8df62c3c41a3d0c288bbf247..804f32a154c6ea7ad54ea7be62fdbb24db09694f 100644
--- a/chrome/browser/sync_file_system/drive_backend/local_to_remote_syncer_unittest.cc
+++ b/chrome/browser/sync_file_system/drive_backend/local_to_remote_syncer_unittest.cc
@@ -91,16 +91,31 @@ class LocalToRemoteSyncerTest : public testing::Test,
   }
 
   void InitializeMetadataDatabase() {
-    SyncEngineInitializer initializer(this,
-                                      base::MessageLoopProxy::current(),
-                                      fake_drive_service_.get(),
-                                      database_dir_.path(),
-                                      in_memory_env_.get());
+    SyncEngineInitializer* initializer =
+        new SyncEngineInitializer(
+            this,
+            base::MessageLoopProxy::current(),
+            fake_drive_service_.get(),
+            database_dir_.path(),
+            in_memory_env_.get());
     SyncStatusCode status = SYNC_STATUS_UNKNOWN;
-    initializer.RunSequential(CreateResultReceiver(&status));
+
+    sync_task_manager_->ScheduleSyncTask(
+        FROM_HERE,
+        scoped_ptr<SyncTask>(initializer),
+        SyncTaskManager::PRIORITY_MED,
+        base::Bind(&LocalToRemoteSyncerTest::DidInitializeMetadataDatabase,
+                   base::Unretained(this), initializer, &status));
+
     base::RunLoop().RunUntilIdle();
     EXPECT_EQ(SYNC_STATUS_OK, status);
-    metadata_database_ = initializer.PassMetadataDatabase();
+  }
+
+  void DidInitializeMetadataDatabase(SyncEngineInitializer* initializer,
+                                     SyncStatusCode* status_out,
+                                     SyncStatusCode status) {
+    *status_out = status;
+    metadata_database_ = initializer->PassMetadataDatabase();
   }
 
   void RegisterApp(const std::string& app_id,