[Extensions Bindings] Add a bindings/ subdirectory under renderer

extensions/renderer/bindings/api_binding_test.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_API_BINDING_TEST_H_
-#define EXTENSIONS_RENDERER_API_BINDING_TEST_H_
+#ifndef EXTENSIONS_RENDERER_BINDINGS_API_BINDING_TEST_H_
+#define EXTENSIONS_RENDERER_BINDINGS_API_BINDING_TEST_H_
 
 #include <memory>
 #include <vector>
 
 #include "base/macros.h"
 #include "base/test/scoped_task_environment.h"
 #include "testing/gtest/include/gtest/gtest.h"
 #include "v8/include/v8.h"
 
 namespace gin {
@@ skipping 45 matching lines @@
 
   std::unique_ptr<gin::IsolateHolder> isolate_holder_;
   std::unique_ptr<gin::ContextHolder> main_context_holder_;
   std::vector<std::unique_ptr<gin::ContextHolder>> additional_context_holders_;
 
   DISALLOW_COPY_AND_ASSIGN(APIBindingTest);
 };
 
 }  // namespace extensions
 
-#endif  // EXTENSIONS_RENDERER_API_BINDING_TEST_H_
+#endif  // EXTENSIONS_RENDERER_BINDINGS_API_BINDING_TEST_H_