BrowserContext should simply own DownloadManager

content/browser/download/download_manager_impl.cc

 // 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.
 
 #include "content/browser/download/download_manager_impl.h"
 
 #include <iterator>
 
 #include "base/bind.h"
 #include "base/callback.h"
@@ skipping 221 matching lines @@
 
 DownloadManagerImpl::DownloadManagerImpl(
     net::NetLog* net_log,
     BrowserContext* browser_context)
     : item_factory_(new DownloadItemFactoryImpl()),
       file_factory_(new DownloadFileFactory()),
       history_size_(0),
       shutdown_needed_(true),
       browser_context_(browser_context),
       delegate_(NULL),
-      net_log_(net_log) {
+      net_log_(net_log),
+      weak_factory_(this) {
   DCHECK(browser_context);
 }
 
 DownloadManagerImpl::~DownloadManagerImpl() {
   DCHECK(!shutdown_needed_);
 }
 
 DownloadItemImpl* DownloadManagerImpl::CreateActiveItem(
     DownloadId id, const DownloadCreateInfo& info) {
   net::BoundNetLog bound_net_log =
@@ skipping 189 matching lines @@
 }
 
 void DownloadManagerImpl::CheckForFileRemoval(DownloadItemImpl* download_item) {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
   if (download_item->IsComplete() &&
       !download_item->GetFileExternallyRemoved() &&
       delegate_) {
     delegate_->CheckForFileExistence(
         download_item,
         base::Bind(&DownloadManagerImpl::OnFileExistenceChecked,
-                   this, download_item->GetId()));
+                   weak_factory_.GetWeakPtr(), download_item->GetId()));
   }
 }
 
 void DownloadManagerImpl::OnFileExistenceChecked(int32 download_id,
                                                  bool result) {
   DCHECK(BrowserThread::CurrentlyOn(BrowserThread::UI));
   if (!result) {  // File does not exist.
     if (ContainsKey(downloads_, download_id))
       downloads_[download_id]->OnDownloadedFileRemoved();
   }
@@ skipping 202 matching lines @@
   if (delegate_)
     delegate_->OpenDownload(download);
 }
 
 void DownloadManagerImpl::ShowDownloadInShell(DownloadItemImpl* download) {
   if (delegate_)
     delegate_->ShowDownloadInShell(download);
 }
 
 }  // namespace content