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

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

Index: chrome/browser/ui/webui/md_downloads/md_downloads_dom_handler.h
diff --git a/chrome/browser/ui/webui/md_downloads/md_downloads_dom_handler.h b/chrome/browser/ui/webui/md_downloads/md_downloads_dom_handler.h
index a724d6db75b9c62faede384484eb4cfdc3f70e72..0aee5da13199ab83d3003d64c4f80e547e7e62dd 100644
--- a/chrome/browser/ui/webui/md_downloads/md_downloads_dom_handler.h
+++ b/chrome/browser/ui/webui/md_downloads/md_downloads_dom_handler.h
@@ -8,10 +8,13 @@
 #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 "chrome/browser/ui/webui/md_downloads/downloads_list_tracker.h"
+#include "content/public/browser/download_item.h"
+#include "content/public/browser/download_manager.h"
 #include "content/public/browser/web_ui_message_handler.h"
 
 namespace base {
@@ -19,25 +22,29 @@
 }
 
 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 {
+class MdDownloadsDOMHandler : public content::WebUIMessageHandler,
+                              public AllDownloadItemNotifier::Observer {
  public:
-  MdDownloadsDOMHandler(content::DownloadManager* download_manager,
-                        content::WebUI* web_ui);
+  explicit MdDownloadsDOMHandler(content::DownloadManager* download_manager);
   ~MdDownloadsDOMHandler() override;
+
+  void Init();
 
   // WebUIMessageHandler implementation.
   void RegisterMessages() override;
 
-  void RenderViewReused(content::RenderViewHost* render_view_host);
+  // 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;
 
   // Callback for the "getDownloads" message.
   void HandleGetDownloads(const base::ListValue* args);
@@ -87,6 +94,12 @@
   // 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();
@@ -102,6 +115,9 @@
   // 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
@@ -128,10 +144,28 @@
   // Remove all downloads in |to_remove| with the ability to undo removal later.
   void RemoveDownloads(const DownloadVector& to_remove);
 
-  DownloadsListTracker list_tracker_;
+  // 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_;
 
   // 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_;