Make DownloadHistory observe manager, items

chrome/browser/download/download_service.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_DOWNLOAD_DOWNLOAD_SERVICE_H_
 #define CHROME_BROWSER_DOWNLOAD_DOWNLOAD_SERVICE_H_
 
 #include <vector>
 
 #include "base/basictypes.h"
 #include "base/callback_forward.h"
 #include "base/memory/ref_counted.h"
+#include "base/memory/scoped_ptr.h"
 #include "chrome/browser/profiles/profile_keyed_service.h"
 
 class ChromeDownloadManagerDelegate;
+class DownloadHistory;
 class Profile;
 
 namespace content {
 class DownloadManager;
 }
 
 // Owning class for ChromeDownloadManagerDelegate.
 class DownloadService : public ProfileKeyedService {
  public:
   explicit DownloadService(Profile* profile);
   virtual ~DownloadService();
 
   // Get the download manager delegate, creating it if it doesn't already exist.
   ChromeDownloadManagerDelegate* GetDownloadManagerDelegate();
 
+  // Get the interface to the history system. Returns NULL if profile is
+  // incognito or if the DownloadManager hasn't been created yet or if there is
+  // no HistoryService for profile.
+  DownloadHistory* GetDownloadHistory();
+
   // Has a download manager been created?
   bool HasCreatedDownloadManager();
 
   // Number of downloads associated with this instance of the service.
   int DownloadCount() const;
 
   // Number of downloads associated with all profiles.
   static int DownloadCountAllProfiles();
 
   // Sets the DownloadManagerDelegate associated with this object and
   // its DownloadManager.  Takes ownership of |delegate|, and destroys
   // the previous delegate.  For testing.
   void SetDownloadManagerDelegateForTesting(
       ChromeDownloadManagerDelegate* delegate);
 
   // Will be called to release references on other services as part
   // of Profile shutdown.
   virtual void Shutdown() OVERRIDE;
 
  private:
   bool download_manager_created_;
   Profile* profile_;
 
   // ChromeDownloadManagerDelegate may be the target of callbacks from
   // the history service/DB thread and must be kept alive for those
   // callbacks.
   scoped_refptr<ChromeDownloadManagerDelegate> manager_delegate_;
 
+  scoped_ptr<DownloadHistory> download_history_;
+
   DISALLOW_COPY_AND_ASSIGN(DownloadService);
 };
 
 #endif  // CHROME_BROWSER_DOWNLOAD_DOWNLOAD_SERVICE_H_