[Extensions Bindings] Add a bridge to use current custom bindings

extensions/renderer/api_binding_bridge.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_BRIDGE_H_
+#define EXTENSIONS_RENDERER_API_BINDING_BRIDGE_H_
+
+#include <string>
+
+#include "base/macros.h"
+#include "extensions/renderer/api_binding_types.h"
+#include "gin/wrappable.h"
+#include "v8/include/v8.h"
+
+namespace extensions {
+
+// An object that serves as a bridge between the current JS-centric bindings and
+// the new native bindings system. This basically needs to conform to the public
+// methods of the Binding prototype in binding.js.
+class APIBindingBridge final : public gin::Wrappable<APIBindingBridge> {
+ public:
+  APIBindingBridge(v8::Local<v8::Context> context,
+                   v8::Local<v8::Value> api_object,
+                   v8::Local<v8::Value> js_hook_interface,
+                   const std::string& extension_id,
+                   const std::string& context_type,
+                   const binding::RunJSFunction& run_js);
+  ~APIBindingBridge() override;
+
+  static gin::WrapperInfo kWrapperInfo;
+
+  // gin::Wrappable:
+  gin::ObjectTemplateBuilder GetObjectTemplateBuilder(
+      v8::Isolate* isolate) final;
+
+ private:
+  // Runs the given function and registers custom hooks.
+  void RegisterCustomHook(v8::Isolate* isolate,
+                          v8::Local<v8::Function> function);

[jbroman, 2016/12/20 20:51:35]

I assume it's documented elsewhere what parameters this function takes, what the
hooks do, etc.? I admit that I get a little lost in this, not having familiarity
with the shape of it.

[Devlin, 2016/12/20 22:20:19]

Added more of a comment.

+
+  // The id of the extension that owns the context this belongs to.
+  std::string extension_id_;
+
+  // The type of context this belongs to.
+  std::string context_type_;
+
+  // A function to run JS safely.
+  binding::RunJSFunction run_js_;
+
+  DISALLOW_COPY_AND_ASSIGN(APIBindingBridge);
+};
+
+}  // namespace extensions
+
+#endif  // EXTENSIONS_RENDERER_API_BINDING_BRIDGE_H_