Hide the process of instantiating NotificationServiceImpl from embedders.

content/browser/notification_service_impl.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 "content/browser/notification_service_impl.h"
 
 #include "base/lazy_instance.h"
 #include "base/threading/thread_local.h"
 #include "content/public/browser/notification_observer.h"
 #include "content/public/browser/notification_types.h"
 
 static base::LazyInstance<base::ThreadLocalPointer<NotificationServiceImpl> >
     lazy_tls_ptr = LAZY_INSTANCE_INITIALIZER;
 
 // static
 NotificationServiceImpl* NotificationServiceImpl::current() {
   return lazy_tls_ptr.Pointer()->Get();
 }
 
 // static
 content::NotificationService* content::NotificationService::current() {
   return NotificationServiceImpl::current();
 }
 
 // static
+content::NotificationService* content::NotificationService::Create() {
+  return new NotificationServiceImpl;
+}
+
+// static
 bool NotificationServiceImpl::HasKey(const NotificationSourceMap& map,
                                  const content::NotificationSource& source) {
   return map.find(source.map_key()) != map.end();
 }
 
 NotificationServiceImpl::NotificationServiceImpl() {
   DCHECK(current() == NULL);
   lazy_tls_ptr.Pointer()->Set(this);
 }
 
@@ skipping 102 matching lines @@
   }
 #endif
 
   for (int i = 0; i < static_cast<int>(observers_.size()); i++) {
     NotificationSourceMap omap = observers_[i];
     for (NotificationSourceMap::iterator it = omap.begin();
          it != omap.end(); ++it)
       delete it->second;
   }
 }