Cleanup headless templates and message_dispatcher.h.

headless/lib/browser/devtools_api/domain_cc.template

 // This file is generated
 
 // Copyright 2016 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 "headless/public/devtools/domains/{{domain.domain | camelcase_to_hacker_style}}.h"
 
 #include "base/bind.h"
+#include "headless/public/util/error_reporter.h"
 
 namespace headless {
 
 namespace {{domain.domain | camelcase_to_hacker_style}} {
 
 ExperimentalDomain* Domain::GetExperimental() {
   return static_cast<ExperimentalDomain*>(this);
 }
 
   {% if "events" in domain %}
@@ skipping 126 matching lines @@
 }
 
 void ExperimentalDomain::RemoveObserver(ExperimentalObserver* observer) {
   observers_.RemoveObserver(observer);
 }
   {% endif %}
 
 }  // namespace {{domain.domain | camelcase_to_hacker_style}}
 
 } // namespace headless