[Sync] Add type conversion constructor for WeakHandle

chrome/browser/sync/profile_sync_service.cc

 // Copyright (c) 2011 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/profile_sync_service.h"
 
 #include <algorithm>
 #include <cstddef>
 #include <map>
 #include <set>
@@ skipping 293 matching lines @@
   SyncCredentials credentials = GetCredentials();
 
   scoped_refptr<net::URLRequestContextGetter> request_context_getter(
       profile_->GetRequestContext());
 
   if (delete_stale_data)
     ClearStaleErrors();
 
   backend_->Initialize(
       this,
-      WeakHandle<JsEventHandler>(sync_js_controller_.AsWeakPtr()),
+      MakeWeakHandle(sync_js_controller_.AsWeakPtr()),
       sync_service_url_,
       initial_types,
       credentials,
       delete_stale_data);
 }
 
 void ProfileSyncService::CreateBackend() {
   backend_.reset(
       new SyncBackendHost(profile_->GetDebugName(),
                           profile_, sync_prefs_.AsWeakPtr()));
@@ skipping 1219 matching lines @@
             << "Unrecoverable error.";
   } else {
     VLOG(0) << "ConfigureDataTypeManager not invoked because backend is not "
             << "initialized";
   }
 }
 
 const FailedDatatypesHandler& ProfileSyncService::failed_datatypes_handler() {
   return failed_datatypes_handler_;
 }