[Sync] Remove backend unrecoverable error handler

chrome/browser/sync/glue/sync_backend_host.h

 // Copyright (c) 2012 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_
 
 #include <string>
 
 #include "base/basictypes.h"
 #include "base/callback.h"
 #include "base/compiler_specific.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/threading/thread.h"
 #include "components/sync_driver/backend_data_type_configurer.h"
 #include "sync/internal_api/public/base/model_type.h"
 #include "sync/internal_api/public/configure_reason.h"
 #include "sync/internal_api/public/sessions/sync_session_snapshot.h"
 #include "sync/internal_api/public/shutdown_reason.h"
 #include "sync/internal_api/public/sync_context_proxy.h"
 #include "sync/internal_api/public/sync_manager.h"
 #include "sync/internal_api/public/sync_manager_factory.h"
-#include "sync/internal_api/public/util/unrecoverable_error_handler.h"
 #include "sync/internal_api/public/util/weak_handle.h"
 
 class GURL;
 
 namespace base {
 class MessageLoop;
 }
 
 namespace syncer {
 class NetworkResources;
 class SyncManagerFactory;
+class UnrecoverableErrorHandler;
 }
 
 namespace sync_driver {
 class ChangeProcessor;
 class SyncFrontend;
 }
 
 namespace browser_sync {
 
 // An API to "host" the top level SyncAPI element.
 //
 // This class handles dispatch of potentially blocking calls to appropriate
 // threads and ensures that the SyncFrontend is only accessed on the UI loop.
 class SyncBackendHost : public sync_driver::BackendDataTypeConfigurer {
  public:
   typedef syncer::SyncStatus Status;
 
   // Stubs used by implementing classes.
   SyncBackendHost();
   ~SyncBackendHost() override;
 
   // Called on the frontend's thread to kick off asynchronous initialization.
   // Optionally deletes the "Sync Data" folder during init in order to make
   // sure we're starting fresh.
   //
-  // Note: |unrecoverable_error_handler| may be invoked from any thread.
-  //
   // |saved_nigori_state| is optional nigori state to restore from a previous
   // backend instance. May be null.
   virtual void Initialize(
       sync_driver::SyncFrontend* frontend,
       scoped_ptr<base::Thread> sync_thread,
       const syncer::WeakHandle<syncer::JsEventHandler>& event_handler,
       const GURL& service_url,
       const syncer::SyncCredentials& credentials,
       bool delete_sync_data_folder,
       scoped_ptr<syncer::SyncManagerFactory> sync_manager_factory,
-      scoped_ptr<syncer::UnrecoverableErrorHandler> unrecoverable_error_handler,
+      const syncer::WeakHandle<syncer::UnrecoverableErrorHandler>&
+          unrecoverable_error_handler,
       const base::Closure& report_unrecoverable_error_function,
       syncer::NetworkResources* network_resources,
       scoped_ptr<syncer::SyncEncryptionHandler::NigoriState>
           saved_nigori_state) = 0;
 
   // Called on the frontend's thread to update SyncCredentials.
   virtual void UpdateCredentials(
       const syncer::SyncCredentials& credentials) = 0;
 
   // This starts the SyncerThread running a Syncer object to communicate with
@@ skipping 142 matching lines @@
   // See SyncManager::ClearServerData.
   virtual void ClearServerData(
       const syncer::SyncManager::ClearServerDataCallback& callback) = 0;
 
   DISALLOW_COPY_AND_ASSIGN(SyncBackendHost);
 };
 
 }  // namespace browser_sync
 
 #endif  // CHROME_BROWSER_SYNC_GLUE_SYNC_BACKEND_HOST_H_