Remove the ability of webpages to specify strings for the onbeforeunload dialog.

extensions/browser/guest_view/web_view/javascript_dialog_helper.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 "extensions/browser/guest_view/web_view/javascript_dialog_helper.h"
 
 #include "base/strings/utf_string_conversions.h"
 #include "base/values.h"
 #include "components/guest_view/common/guest_view_constants.h"
 #include "extensions/browser/guest_view/web_view/web_view_constants.h"
@@ skipping 54 matching lines @@
       WEB_VIEW_PERMISSION_TYPE_JAVASCRIPT_DIALOG,
       request_info,
       base::Bind(&JavaScriptDialogHelper::OnPermissionResponse,
                  base::Unretained(this),
                  callback),
       false /* allowed_by_default */);
 }
 
 void JavaScriptDialogHelper::RunBeforeUnloadDialog(
     content::WebContents* web_contents,
-    const base::string16& message_text,
     bool is_reload,
     const DialogClosedCallback& callback) {
   // This is called if the guest has a beforeunload event handler.
   // This callback allows navigation to proceed.
   callback.Run(true, base::string16());
 }
 
 bool JavaScriptDialogHelper::HandleJavaScriptDialog(
     content::WebContents* web_contents,
     bool accept,
@@ skipping 11 matching lines @@
 
 void JavaScriptDialogHelper::OnPermissionResponse(
     const DialogClosedCallback& callback,
     bool allow,
     const std::string& user_input) {
   callback.Run(allow && web_view_guest_->attached(),
                base::UTF8ToUTF16(user_input));
 }
 
 }  // namespace extensions