[Extensions] DCHECK that ExtensionFunctions respond (and only once)

chrome/browser/extensions/api/web_view/chrome_web_view_internal_api.cc

 // Copyright 2014 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 "chrome/browser/extensions/api/web_view/chrome_web_view_internal_api.h"
 
 #include "chrome/browser/extensions/api/context_menus/context_menus_api.h"
 #include "chrome/browser/extensions/api/context_menus/context_menus_api_helpers.h"
 #include "chrome/browser/profiles/profile.h"
 #include "chrome/common/extensions/api/chrome_web_view_internal.h"
@@ skipping 122 matching lines @@
 }
 
 ChromeWebViewInternalShowContextMenuFunction::
     ChromeWebViewInternalShowContextMenuFunction() {
 }
 
 ChromeWebViewInternalShowContextMenuFunction::
     ~ChromeWebViewInternalShowContextMenuFunction() {
 }
 
-bool ChromeWebViewInternalShowContextMenuFunction::RunAsyncSafe(
-    WebViewGuest* guest) {
+ExtensionFunction::ResponseAction
+ChromeWebViewInternalShowContextMenuFunction::Run() {
   std::unique_ptr<webview::ShowContextMenu::Params> params(
       webview::ShowContextMenu::Params::Create(*args_));
   EXTENSION_FUNCTION_VALIDATE(params.get());
 
   // TODO(lazyboy): Actually implement filtering menu items.
-  guest->ShowContextMenu(params->request_id);
-
-  SendResponse(true);
-  return true;
+  guest_->ShowContextMenu(params->request_id);
+  return RespondNow(NoArguments());
 }
 
 }  // namespace extensions