[Sync] Refactored ProfileSyncService and remove its backend() function

chrome/browser/sync/glue/sync_backend_host.h

 // Copyright (c) 2010 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.
 
 #ifndef CHROME_BROWSER_SYNC_GLUE_SYNC_BACKEND_HOST_H_
 #define CHROME_BROWSER_SYNC_GLUE_SYNC_BACKEND_HOST_H_
 #pragma once
 
 #include <map>
 #include <string>
@@ skipping 89 matching lines @@
  public:
   typedef sync_api::UserShare* UserShareHandle;
   typedef sync_api::SyncManager::Status::Summary StatusSummary;
   typedef sync_api::SyncManager::Status Status;
   typedef std::map<ModelSafeGroup,
                    scoped_refptr<browser_sync::ModelSafeWorker> > WorkerMap;
 
   // Create a SyncBackendHost with a reference to the |frontend| that it serves
   // and communicates to via the SyncFrontend interface (on the same thread
   // it used to call the constructor).
-  SyncBackendHost(SyncFrontend* frontend, Profile* profile);
+  explicit SyncBackendHost(Profile* profile);
   // For testing.
   // TODO(skrul): Extract an interface so this is not needed.
   SyncBackendHost();
   ~SyncBackendHost();
 
   // Called on |frontend_loop_| to kick off asynchronous initialization.
   // As a fallback when no cached auth information is available, try to
   // bootstrap authentication using |lsid|, if it isn't empty.
   // Optionally delete the Sync Data folder (if it's corrupt).
-  void Initialize(const GURL& service_url,
+  void Initialize(SyncFrontend* frontend,
+                  const GURL& service_url,
                   const syncable::ModelTypeSet& types,
                   URLRequestContextGetter* baseline_context_getter,
                   const sync_api::SyncCredentials& credentials,
                   bool delete_sync_data_folder,
                   const notifier::NotifierOptions& notifier_options);
 
   // Called from |frontend_loop| to update SyncCredentials.
   void UpdateCredentials(const sync_api::SyncCredentials& credentials);
 
   // This starts the SyncerThread running a Syncer object to communicate with
@@ skipping 403 matching lines @@
 
   // Whether we've processed the initialization complete callback.
   bool syncapi_initialized_;
 
   DISALLOW_COPY_AND_ASSIGN(SyncBackendHost);
 };
 
 }  // namespace browser_sync
 
 #endif  // CHROME_BROWSER_SYNC_GLUE_SYNC_BACKEND_HOST_H_