BrowserContext should simply own DownloadManager

content/public/browser/download_manager.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.
 //
 // The DownloadManager object manages the process of downloading, including
 // updates to the history system and providing the information for displaying
 // the downloads view in the Destinations tab. There is one DownloadManager per
 // active browser context in Chrome.
 //
 // Download observers:
@@ skipping 38 matching lines @@
 class BrowserContext;
 class ByteStreamReader;
 class DownloadManagerDelegate;
 class DownloadQuery;
 class DownloadRequestHandle;
 class DownloadUrlParameters;
 struct DownloadCreateInfo;
 struct DownloadRetrieveInfo;
 
 // Browser's download manager: manages all downloads and destination view.
-class CONTENT_EXPORT DownloadManager
-    : public base::RefCountedThreadSafe<DownloadManager> {
+class CONTENT_EXPORT DownloadManager : public base::SupportsUserData::Data {
  public:
+  virtual ~DownloadManager() {}
+
   // Sets/Gets the delegate for this DownloadManager. The delegate has to live
   // past its Shutdown method being called (by the DownloadManager).
   virtual void SetDelegate(DownloadManagerDelegate* delegate) = 0;
   virtual DownloadManagerDelegate* GetDelegate() const = 0;
 
   // Shutdown the download manager. Content calls this when BrowserContext is
   // being destructed. If the embedder needs this to be called earlier, it can
   // call it. In that case, the delegate's Shutdown() method will only be called
   // once.
   virtual void Shutdown() = 0;
@@ skipping 90 matching lines @@
   virtual BrowserContext* GetBrowserContext() const = 0;
 
   // Checks whether downloaded files still exist. Updates state of downloads
   // that refer to removed files. The check runs in the background and may
   // finish asynchronously after this method returns.
   virtual void CheckForHistoryFilesRemoval() = 0;
 
   // Get the download item for |id| if present, no matter what type of download
   // it is or state it's in.
   virtual DownloadItem* GetDownload(int id) = 0;
-
- protected:
-  virtual ~DownloadManager() {}
-
- private:
-  friend class base::RefCountedThreadSafe<DownloadManager>;
 };
 
 }  // namespace content
 
 #endif  // CONTENT_PUBLIC_BROWSER_DOWNLOAD_MANAGER_H_