[Extension Bindings] Add JS custom hook support

extensions/renderer/api_binding_hooks.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_HOOKS_H_
 #define EXTENSIONS_RENDERER_API_BINDING_HOOKS_H_
 
 #include <map>
 #include <memory>
 #include <string>
@@ skipping 20 matching lines @@
   // (so the caller can verify arguments, optionally after modifying/"massaging"
   // them) and the passed arguments. The handler is responsible for returning,
   // which depending on the API could mean either returning synchronously
   // through gin::Arguments::Return or asynchronously through a passed callback.
   // TODO(devlin): As we continue expanding the hooks interface, we should allow
   // handlers to register a request so that they don't have to maintain a
   // reference to the callback themselves.
   using HandleRequestHook =
       base::Callback<void(const binding::APISignature*, gin::Arguments*)>;
 
-  APIBindingHooks();
+  explicit APIBindingHooks(const binding::RunJSFunction& run_js);
   ~APIBindingHooks();
 
   // Register a custom binding to handle requests.
   void RegisterHandleRequest(const std::string& method_name,
                              const HandleRequestHook& hook);
 
+  // Registers a JS script to be compiled and run in order to initialize any JS
+  // hooks within a v8 context.
+  void RegisterJsSource(v8::Global<v8::String> source);
+
+  // Initializes JS hooks within a context.
+  void InitializeInContext(v8::Local<v8::Context> context,
+                           const std::string& api_name);
+
   // Returns the custom hook for the given method, or a null callback if none
   // exists.
-  HandleRequestHook GetHandleRequest(const std::string& method_name);
+  HandleRequestHook GetHandleRequest(const std::string& api_name,
+                                     const std::string& method_name,
+                                     v8::Local<v8::Context> context);
 
  private:
   // All registered request handlers.
   std::map<std::string, HandleRequestHook> request_hooks_;
 
+  // The script to run to initialize JS hooks, if any.
+  v8::Global<v8::String> js_hooks_source_;
+
+  binding::RunJSFunction run_js_;
+
   DISALLOW_COPY_AND_ASSIGN(APIBindingHooks);
 };
 
 }  // namespace extensions
 
 #endif  // EXTENSIONS_RENDERER_API_BINDING_HOOKS_H_