[Extensions Bindings] Move custom handling to APIBindingHooksDelegate

extensions/renderer/api_binding_hooks_delegate.h

 // 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.
 
 #ifndef EXTENSIONS_RENDERER_API_BINDING_HOOKS_DELEGATE_H_
 #define EXTENSIONS_RENDERER_API_BINDING_HOOKS_DELEGATE_H_
 
+#include "extensions/renderer/api_binding_hooks.h"
 #include "extensions/renderer/api_binding_types.h"
 #include "v8/include/v8.h"
 
 namespace extensions {
 
 // A per-API set of custom hooks to override the default behavior.
 class APIBindingHooksDelegate {
  public:
   virtual ~APIBindingHooksDelegate();
 
   // Allows custom implementations to return a different event object.
   // Populates |event_out| and returns true if a custom implementation should
   // be used, otherwise returns false.
   virtual bool CreateCustomEvent(v8::Local<v8::Context> context,
                                  const binding::RunJSFunctionSync& run_js_sync,
                                  const std::string& event_name,
                                  v8::Local<v8::Value>* event_out);
 
-  // TODO(devlin): Add a virtual HandleRequest() method.
+  // Allows custom implementations to handle a given request.
+  virtual APIBindingHooks::RequestResult HandleRequest(
+      const std::string& method_name,
+      const APISignature* signature,
+      v8::Local<v8::Context> context,
+      std::vector<v8::Local<v8::Value>>* arguments,
+      const APITypeReferenceMap& refs);
 };
 
 }  // namespace extensions
 
 #endif  // EXTENSIONS_RENDERER_API_BINDING_HOOKS_DELEGATE_H_