[Extensions Bindings] Add a bindings/ subdirectory under renderer

extensions/renderer/api_binding_types.cc

Index: extensions/renderer/api_binding_types.cc
diff --git a/extensions/renderer/api_binding_types.cc b/extensions/renderer/api_binding_types.cc
deleted file mode 100644
index e354d8b471bd56ae65796e83188c6c8c4ce740da..0000000000000000000000000000000000000000
--- a/extensions/renderer/api_binding_types.cc
+++ /dev/null
@@ -1,13 +0,0 @@
-// Copyright 2017 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 "extensions/renderer/api_binding_types.h"
-
-namespace extensions {
-namespace binding {
-
-const int kNoListenerMax = -1;
-
-}  // namespace binding
-}  // namespace extensions