Plumb Blink notification actions to button UI on desktop

components/html_viewer/web_notification_manager_impl.cc

 // Copyright 2015 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 "components/html_viewer/web_notification_manager_impl.h"
 
 #include "base/logging.h"
 
 namespace html_viewer {
 
@@ skipping 42 matching lines @@
     blink::WebNotificationDelegate*) {
   NOTIMPLEMENTED();
 }
 
 blink::WebNotificationPermission WebNotificationManagerImpl::checkPermission(
     const blink::WebSecurityOrigin&) {
   NOTIMPLEMENTED();
   return blink::WebNotificationPermission();
 }
 
+size_t NotificationManager::maxActions() {
+  NOTIMPLEMENTED();
+  return 0;
+}
+
 }  // namespace html_viewer