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

chrome/browser/ui/webui/md_downloads/downloads_list_tracker.h

-// Copyright 2015 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_DOWNLOADS_LIST_TRACKER_H_
-#define CHROME_BROWSER_UI_WEBUI_MD_DOWNLOADS_DOWNLOADS_LIST_TRACKER_H_
-
-#include <set>
-
-#include "base/callback_forward.h"
-#include "base/macros.h"
-#include "base/memory/scoped_ptr.h"
-#include "base/strings/string16.h"
-#include "base/time/time.h"
-#include "base/values.h"
-#include "chrome/browser/download/all_download_item_notifier.h"
-#include "content/public/browser/download_item.h"
-
-namespace base {
-class DictionaryValue;
-class ListValue;
-}
-
-namespace content {
-class DownloadManager;
-class WebUI;
-}
-
-// A class that tracks all downloads activity and keeps a sorted representation
-// of the downloads as chrome://downloads wants to display them.
-class DownloadsListTracker : public AllDownloadItemNotifier::Observer {
- public:
-  DownloadsListTracker(content::DownloadManager* download_manager,
-                       content::WebUI* web_ui);
-  ~DownloadsListTracker() override;
-
-  // Clears all downloads on the page (if it's ready).
-  void CallClearAll();
-
-  // Shows only downloads that match |search_terms|. An empty list shows all
-  // downloads. Returns whether |search_terms.Equals(&search_terms_)|.
-  bool SetSearchTerms(const base::ListValue& search_terms);
-
-  // Sends all downloads and enables updates.
-  void Start();
-
-  // Stops sending updates to the page.
-  void Stop();
-
-  content::DownloadManager* GetMainNotifierManager() const;
-  content::DownloadManager* GetOriginalNotifierManager() const;
-
-  // AllDownloadItemNotifier::Observer:
-  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;
-
- protected:
-  // Testing constructor.
-  DownloadsListTracker(content::DownloadManager* download_manager,
-                       content::WebUI* web_ui,
-                       base::Callback<bool(const content::DownloadItem&)>);
-
-  // Creates a dictionary value that's sent to the page as JSON.
-  virtual scoped_ptr<base::DictionaryValue> CreateDownloadItemValue(
-      content::DownloadItem* item) const;
-
-  const content::DownloadItem* GetItemForTesting(size_t index) const;
-
- private:
-  struct StartTimeComparator {
-    bool operator() (const content::DownloadItem* a,
-                     const content::DownloadItem* b) const;
-  };
-  using SortedSet = std::set<content::DownloadItem*, StartTimeComparator>;
-
-  // Called by both constructors to initialize common state.
-  void Init();
-
-  // Clears and re-inserts all visible items in a sorted order into
-  // |sorted_visible_items_|.
-  void RebuildSortedSet();
-
-  // Whether |item| should show on the current page.
-  bool ShouldShow(const content::DownloadItem& item) const;
-
-  // Gets a page index for |position| from |sorted_visible_items_|.
-  int GetIndex(const SortedSet::iterator& position) const;
-
-  // Calls "insertItems" if |sending_updates_|.
-  void CallInsertItem(const SortedSet::iterator& insert);
-
-  // Calls "updateItem" if |sending_updates_|.
-  void CallUpdateItem(const SortedSet::iterator& update);
-
-  // Removes the item that corresponds to |remove| and sends a "removeItems"
-  // message to the page if |sending_updates_|.
-  void RemoveItem(const SortedSet::iterator& remove);
-
-  AllDownloadItemNotifier main_notifier_;
-  scoped_ptr<AllDownloadItemNotifier> original_notifier_;
-
-  // The WebUI object corresponding to the page we care about.
-  content::WebUI* const web_ui_;
-
-  // Callback used to determine if an item should show on the page. Set to
-  // |ShouldShow()| in default constructor, passed in while testing.
-  base::Callback<bool(const content::DownloadItem&)> should_show_;
-
-  // When this is true, all changes to downloads that affect the page are sent
-  // via JavaScript.
-  bool sending_updates_ = false;
-
-  SortedSet sorted_visible_items_;
-
-  // Current search terms.
-  std::vector<base::string16> search_terms_;
-
-  DISALLOW_COPY_AND_ASSIGN(DownloadsListTracker);
-};
-
-#endif  // CHROME_BROWSER_UI_WEBUI_MD_DOWNLOADS_DOWNLOADS_LIST_TRACKER_H_