Created a DownloadManager interface, for use in unit tests..

content/shell/shell_browser_context.cc

 // 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.
 
 #include "content/shell/shell_browser_context.h"
 
 #include "base/file_util.h"
 #include "base/logging.h"
 #include "base/path_service.h"
 #include "content/browser/appcache/chrome_appcache_service.h"
@@ skipping 108 matching lines @@
   if (!ssl_host_state_.get())
     ssl_host_state_.reset(new SSLHostState());
   return ssl_host_state_.get();
 }
 
 DownloadManager* ShellBrowserContext::GetDownloadManager()  {
   if (!download_manager_.get()) {
     download_status_updater_.reset(new DownloadStatusUpdater());
 
     download_manager_delegate_ = new ShellDownloadManagerDelegate();
-    download_manager_ = new DownloadManager(download_manager_delegate_,
-                                            download_id_factory_,
-                                            download_status_updater_.get());
+    download_manager_ = new DownloadManagerImpl(download_manager_delegate_,
+                                                download_id_factory_,
+                                                download_status_updater_.get());
     download_manager_delegate_->SetDownloadManager(download_manager_.get());
     download_manager_->Init(this);
   }
   return download_manager_.get();
 }
 
 net::URLRequestContextGetter* ShellBrowserContext::GetRequestContext()  {
   if (!url_request_getter_) {
     url_request_getter_ = new ShellURLRequestContextGetter(
         GetPath(),
@@ skipping 111 matching lines @@
     NewRunnableMethod(
         appcache_service_.get(),
         &ChromeAppCacheService::InitializeOnIOThread,
         IsOffTheRecord()
             ? FilePath() : GetPath().Append(FILE_PATH_LITERAL("AppCache")),
         &GetResourceContext(),
         special_storage_policy));
 }
 
 }  // namespace content