Reland part of r62043 that got reverted.

chrome/browser/download/download_manager.cc

 // Copyright (c) 2010 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.
 
 #include "chrome/browser/download/download_manager.h"
 
 #include "app/l10n_util.h"
 #include "app/resource_bundle.h"
 #include "base/callback.h"
 #include "base/file_util.h"
@@ skipping 62 matching lines @@
   if (!shutdown_needed_)
     return;
   shutdown_needed_ = false;
 
   FOR_EACH_OBSERVER(Observer, observers_, ManagerGoingDown());
 
   if (file_manager_) {
     BrowserThread::PostTask(BrowserThread::FILE, FROM_HERE,
         NewRunnableMethod(file_manager_,
                           &DownloadFileManager::OnDownloadManagerShutdown,
-                          this));
+                          make_scoped_refptr(this)));
   }
 
   AssertContainersConsistent();
 
   // Go through all downloads in downloads_.  Dangerous ones we need to
   // remove on disk, and in progress ones we need to cancel.
   for (std::set<DownloadItem*>::iterator it = downloads_.begin();
        it != downloads_.end();) {
     DownloadItem* download = *it;
 
@@ skipping 347 matching lines @@
            << " info = " << info->DebugString();
 
   if (download_finished || info->is_dangerous) {
     // The download has already finished or the download is not safe.
     // We can now rename the file to its final name (or its tentative name
     // in dangerous download cases).
     BrowserThread::PostTask(
         BrowserThread::FILE, FROM_HERE,
         NewRunnableMethod(
             file_manager_, &DownloadFileManager::OnFinalDownloadName,
-            download->id(), target_path, !info->is_dangerous, this));
+            download->id(), target_path, !info->is_dangerous,
+            make_scoped_refptr(this)));
   } else {
     // The download hasn't finished and it is a safe download.  We need to
     // rename it to its intermediate '.crdownload' path.
     FilePath download_path = download_util::GetCrDownloadPath(target_path);
     BrowserThread::PostTask(
         BrowserThread::FILE, FROM_HERE,
         NewRunnableMethod(
             file_manager_, &DownloadFileManager::OnIntermediateDownloadName,
-            download->id(), download_path, this));
+            download->id(), download_path, make_scoped_refptr(this)));
     download->Rename(download_path);
   }
 
   if (download_finished) {
     // If the download already completed by the time we reached this point, then
     // notify observers that it did.
     OnAllDataSaved(info->download_id,
                    pending_finished_downloads_[info->download_id]);
   }
 
@@ skipping 561 matching lines @@
     observed_download_manager_->RemoveObserver(this);
 }
 
 void DownloadManager::OtherDownloadManagerObserver::ModelChanged() {
   observing_download_manager_->NotifyModelChanged();
 }
 
 void DownloadManager::OtherDownloadManagerObserver::ManagerGoingDown() {
   observed_download_manager_ = NULL;
 }