WebUI: Add JavaScript lifecycle-control to WebUIMessageHandler.

chrome/browser/ui/webui/md_downloads/md_downloads_dom_handler.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 CHROME_BROWSER_UI_WEBUI_MD_DOWNLOADS_MD_DOWNLOADS_DOM_HANDLER_H_
 #define CHROME_BROWSER_UI_WEBUI_MD_DOWNLOADS_MD_DOWNLOADS_DOM_HANDLER_H_
 
 #include <stdint.h>
 
 #include <set>
@@ skipping 20 matching lines @@
 // The handler for Javascript messages related to the "downloads" view,
 // also observes changes to the download manager.
 class MdDownloadsDOMHandler : public content::WebUIMessageHandler {
  public:
   MdDownloadsDOMHandler(content::DownloadManager* download_manager,
                         content::WebUI* web_ui);
   ~MdDownloadsDOMHandler() override;
 
   // WebUIMessageHandler implementation.
   void RegisterMessages() override;
-  void RenderViewReused() override;
+  void OnJavascriptAllowed() override;
+  void OnJavascriptDisallowed() override;
 
   // Callback for the "getDownloads" message.
   void HandleGetDownloads(const base::ListValue* args);
 
   // Callback for the "openFile" message - opens the file in the shell.
   void HandleOpenFile(const base::ListValue* args);
 
   // Callback for the "drag" message - initiates a file object drag.
   void HandleDrag(const base::ListValue* args);
 
@@ skipping 84 matching lines @@
 
   // IDs of downloads to remove when this handler gets deleted.
   std::vector<IdSet> removals_;
 
   base::WeakPtrFactory<MdDownloadsDOMHandler> weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(MdDownloadsDOMHandler);
 };
 
 #endif  // CHROME_BROWSER_UI_WEBUI_MD_DOWNLOADS_MD_DOWNLOADS_DOM_HANDLER_H_