[Extensions Bindings] Add a bindings/ subdirectory under renderer

extensions/renderer/bindings/event_emitter.h

 // 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.
 
-#ifndef EXTENSIONS_RENDERER_EVENT_EMITTER_H_
-#define EXTENSIONS_RENDERER_EVENT_EMITTER_H_
+#ifndef EXTENSIONS_RENDERER_BINDINGS_EVENT_EMITTER_H_
+#define EXTENSIONS_RENDERER_BINDINGS_EVENT_EMITTER_H_
 
 #include <vector>
 
-#include "extensions/renderer/api_binding_types.h"
+#include "extensions/renderer/bindings/api_binding_types.h"
 #include "gin/wrappable.h"
 #include "v8/include/v8.h"
 
 namespace gin {
 class Arguments;
 }
 
 namespace extensions {
 class APIEventListeners;
 struct EventFilteringInfo;
@@ skipping 54 matching lines @@
   std::unique_ptr<APIEventListeners> listeners_;
 
   binding::RunJSFunction run_js_;
   binding::RunJSFunctionSync run_js_sync_;
 
   DISALLOW_COPY_AND_ASSIGN(EventEmitter);
 };
 
 }  // namespace extensions
 
-#endif  // EXTENSIONS_RENDERER_EVENT_EMITTER_H_
+#endif  // EXTENSIONS_RENDERER_BINDINGS_EVENT_EMITTER_H_