Refactor downloads into a ProfileKeyedService.

content/browser/download/download_manager_delegate.h

 // Copyright (c) 2011 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 CONTENT_BROWSER_DOWNLOAD_DOWNLOAD_MANAGER_DELEGATE_H_
 #define CONTENT_BROWSER_DOWNLOAD_DOWNLOAD_MANAGER_DELEGATE_H_
 #pragma once
 
 #include "base/basictypes.h"
 #include "base/memory/weak_ptr.h"
 #include "base/time.h"
 
 class DownloadItem;
+class DownloadManager;
 class FilePath;
 class TabContents;
 class SavePackage;
 
 // Browser's download manager: manages all downloads and destination view.
 class DownloadManagerDelegate {
  public:
   virtual ~DownloadManagerDelegate() {}
 
   // Lets the delegate know that the download manager is shutting down.
@@ skipping 74 matching lines @@
 
   // Asks the user for the path to save a page. The delegate calls
   // SavePackage::OnPathPicked to give the answer.
   virtual void ChooseSavePath(const base::WeakPtr<SavePackage>& save_package,
                               const FilePath& suggested_path,
                               bool can_save_as_complete) = 0;
 
   // Informs the delegate that the progress of downloads has changed.
   virtual void DownloadProgressUpdated() = 0;
 
+  // Tell the delegate what manager it's delegating for;
+  // only called by the DownloadManager.
+  virtual void SetDownloadManager(DownloadManager* manager) = 0;

[jam, 2011/10/10 18:19:33]

this pattern of having the delegate be told by the object that it's been set is
not something we do with our other delegates. is this really necessary or can we
just do this manually? not all embedders might care to have the DownloadManager
pointer

[Randy Smith (Not in Mondays), 2011/10/11 18:24:43]

Yeah.  This is to make the test code simpler--it allows us to replace delegates
on the download manage and have the right thing happen with a single call (set
the DM delegate and have the DM tell the delegate what DM it's delegating for). 
But I agree that it's worth a fair amount of complexity in test code to make
production code simpler, so I'll change it.  It's just producing more fragile
test code.  

+
  protected:
   DownloadManagerDelegate() {}
 
   DISALLOW_COPY_AND_ASSIGN(DownloadManagerDelegate);
 };
 
 #endif  // CONTENT_BROWSER_DOWNLOAD_DOWNLOAD_MANAGER_DELEGATE_H_