MD Downloads: track downloads in C++, dispatch discrete JS updates

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 <set>
 #include <vector>
 
-#include "base/compiler_specific.h"
 #include "base/macros.h"
 #include "base/memory/weak_ptr.h"
-#include "chrome/browser/download/all_download_item_notifier.h"
 #include "chrome/browser/download/download_danger_prompt.h"
-#include "content/public/browser/download_item.h"
-#include "content/public/browser/download_manager.h"
+#include "chrome/browser/ui/webui/md_downloads/downloads_list_tracker.h"
 #include "content/public/browser/web_ui_message_handler.h"
 
 namespace base {
 class ListValue;
 }
 
 namespace content {
+class DownloadItem;
+class DownloadManager;
+class RenderViewHost;
 class WebContents;
+class WebUI;
 }
 
 // The handler for Javascript messages related to the "downloads" view,
 // also observes changes to the download manager.
-class MdDownloadsDOMHandler : public content::WebUIMessageHandler,
-                              public AllDownloadItemNotifier::Observer {
+class MdDownloadsDOMHandler : public content::WebUIMessageHandler {
  public:
-  explicit MdDownloadsDOMHandler(content::DownloadManager* download_manager);
+  MdDownloadsDOMHandler(content::DownloadManager* download_manager,
+                        content::WebUI* web_ui);
   ~MdDownloadsDOMHandler() override;
 
-  void Init();
-
   // WebUIMessageHandler implementation.
   void RegisterMessages() override;
 
-  // AllDownloadItemNotifier::Observer interface
-  void OnDownloadCreated(content::DownloadManager* manager,
-                         content::DownloadItem* download_item) override;
-  void OnDownloadUpdated(content::DownloadManager* manager,
-                         content::DownloadItem* download_item) override;
-  void OnDownloadRemoved(content::DownloadManager* manager,
-                         content::DownloadItem* download_item) override;
+  void RenderViewReused(content::RenderViewHost* render_view_host);
 
   // 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 29 matching lines @@
 
   // Callback for the "openDownloadsFolder" message - opens the downloads
   // folder.
   void HandleOpenDownloadsFolder(const base::ListValue* args);
 
  protected:
   // These methods are for mocking so that most of this class does not actually
   // depend on WebUI. The other methods that depend on WebUI are
   // RegisterMessages() and HandleDrag().
   virtual content::WebContents* GetWebUIWebContents();
-  virtual void CallUpdateAll(const base::ListValue& list);
-  virtual void CallUpdateItem(const base::DictionaryValue& item);
-
-  // Schedules a call to SendCurrentDownloads() in the next message loop
-  // iteration. Protected rather than private for use in tests.
-  void ScheduleSendCurrentDownloads();
 
   // Actually remove downloads with an ID in |removals_|. This cannot be undone.
   void FinalizeRemovals();
 
  private:
   using IdSet = std::set<uint32>;
   using DownloadVector = std::vector<content::DownloadItem*>;
 
   // Convenience method to call |main_notifier_->GetManager()| while
   // null-checking |main_notifier_|.
   content::DownloadManager* GetMainNotifierManager() const;
 
   // Convenience method to call |original_notifier_->GetManager()| while
   // null-checking |original_notifier_|.
   content::DownloadManager* GetOriginalNotifierManager() const;
 
-  // Sends the current list of downloads to the page.
-  void SendCurrentDownloads();
-
   // Displays a native prompt asking the user for confirmation after accepting
   // the dangerous download specified by |dangerous|. The function returns
   // immediately, and will invoke DangerPromptAccepted() asynchronously if the
   // user accepts the dangerous download. The native prompt will observe
   // |dangerous| until either the dialog is dismissed or |dangerous| is no
   // longer an in-progress dangerous download.
   void ShowDangerPrompt(content::DownloadItem* dangerous);
 
   // Conveys danger acceptance from the DownloadDangerPrompt to the
   // DownloadItem.
   void DangerPromptDone(int download_id, DownloadDangerPrompt::Action action);
 
   // Returns true if the records of any downloaded items are allowed (and able)
   // to be deleted.
   bool IsDeletingHistoryAllowed();
 
   // Returns the download that is referred to in a given value.
   content::DownloadItem* GetDownloadByValue(const base::ListValue* args);
 
   // Returns the download with |id| or NULL if it doesn't exist.
   content::DownloadItem* GetDownloadById(uint32 id);
 
   // Remove all downloads in |to_remove| with the ability to undo removal later.
   void RemoveDownloads(const DownloadVector& to_remove);
 
-  // Weak reference to the DownloadManager this class was constructed with. You
-  // should probably be using use Get{Main,Original}NotifierManager() instead.
-  content::DownloadManager* download_manager_;
-
-  // Current search terms.
-  scoped_ptr<base::ListValue> search_terms_;
-
-  // Notifies OnDownload*() and provides safe access to the DownloadManager.
-  scoped_ptr<AllDownloadItemNotifier> main_notifier_;
-
-  // If |main_notifier_| observes an incognito profile, then this observes the
-  // DownloadManager for the original profile; otherwise, this is NULL.
-  scoped_ptr<AllDownloadItemNotifier> original_notifier_;
+  DownloadsListTracker list_tracker_;
 
   // IDs of downloads to remove when this handler gets deleted.
   std::vector<IdSet> removals_;
 
-  // Whether a call to SendCurrentDownloads() is currently scheduled.
-  bool update_scheduled_;
-
-  // IDs of new downloads that the page doesn't know about yet.
-  IdSet new_downloads_;
-
   base::WeakPtrFactory<MdDownloadsDOMHandler> weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(MdDownloadsDOMHandler);
 };
 
 #endif  // CHROME_BROWSER_UI_WEBUI_MD_DOWNLOADS_MD_DOWNLOADS_DOM_HANDLER_H_