[Extension Bindings] Add JS custom hook support

extensions/renderer/api_binding_hooks.h

Index: extensions/renderer/api_binding_hooks.h
diff --git a/extensions/renderer/api_binding_hooks.h b/extensions/renderer/api_binding_hooks.h
index 37f41fc467ff0e065c8634db92f4761a7db77f61..815e6a36ddd667dd830b2f1201a9c2f0737fdcd6 100644
--- a/extensions/renderer/api_binding_hooks.h
+++ b/extensions/renderer/api_binding_hooks.h
@@ -38,21 +38,36 @@ class APIBindingHooks {
   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);
 };