[Extensions Bindings] Add a bindings/ subdirectory under renderer

extensions/renderer/bindings/api_binding_test_util.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_UTIL_H_
-#define EXTENSIONS_RENDERER_API_BINDING_TEST_UTIL_H_
+#ifndef EXTENSIONS_RENDERER_BINDINGS_API_BINDING_TEST_UTIL_H_
+#define EXTENSIONS_RENDERER_BINDINGS_API_BINDING_TEST_UTIL_H_
 
 #include <memory>
 #include <string>
 
 #include "base/strings/string_piece.h"
 #include "v8/include/v8.h"
 
 namespace base {
 class DictionaryValue;
 class ListValue;
@@ skipping 103 matching lines @@
     base::StringPiece key);
 
 // As above, but returns a JSON-serialized version of the value, or
 // "undefined", "null", "function", or "empty".
 std::string GetStringPropertyFromObject(v8::Local<v8::Object> object,
                                         v8::Local<v8::Context> context,
                                         base::StringPiece key);
 
 }  // extensions
 
-#endif  // EXTENSIONS_RENDERER_API_BINDING_TEST_UTIL_H_
+#endif  // EXTENSIONS_RENDERER_BINDINGS_API_BINDING_TEST_UTIL_H_