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

android_webview/browser/aw_javascript_dialog_manager.h

 // Copyright (c) 2012 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 ANDROID_WEBVIEW_BROWSER_AW_JAVASCRIPT_DIALOG_MANAGER_H_
 #define ANDROID_WEBVIEW_BROWSER_AW_JAVASCRIPT_DIALOG_MANAGER_H_
 
 #include "base/macros.h"
 #include "content/public/browser/javascript_dialog_manager.h"
 
 namespace android_webview {
 
 class AwJavaScriptDialogManager : public content::JavaScriptDialogManager {
  public:
   explicit AwJavaScriptDialogManager();
   ~AwJavaScriptDialogManager() override;
 
   // Overridden from content::JavaScriptDialogManager:
   void RunJavaScriptDialog(content::WebContents* web_contents,
                            const GURL& origin_url,
                            const std::string& accept_lang,
                            content::JavaScriptMessageType message_type,
                            const base::string16& message_text,
                            const base::string16& default_prompt_text,
                            const DialogClosedCallback& callback,
                            bool* did_suppress_message) override;
   void RunBeforeUnloadDialog(content::WebContents* web_contents,
-                             const base::string16& message_text,
                              bool is_reload,
                              const DialogClosedCallback& callback) override;
   void CancelActiveAndPendingDialogs(
       content::WebContents* web_contents) override;
   void ResetDialogState(content::WebContents* web_contents) override;
 
  private:
   DISALLOW_COPY_AND_ASSIGN(AwJavaScriptDialogManager);
 };
 
 }  // namespace android_webview
 
 #endif  // ANDROID_WEBVIEW_BROWSER_AW_JAVASCRIPT_DIALOG_MANAGER_H_