Remove DownloadFileManager in favor of direct ownership of DownloadFiles.

content/browser/download/mock_download_file.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/mock_download_file.h"
 
 using ::testing::_;
 using ::testing::Return;
 
+namespace {
+
+void SuccessRun(content::DownloadFile::InitializeCallback callback) {
+  callback.Run(content::DOWNLOAD_INTERRUPT_REASON_NONE);
+}
+
+}  // namespace
+
 MockDownloadFile::MockDownloadFile() {
   // This is here because |Initialize()| is normally called right after
   // construction.
-  ON_CALL(*this, Initialize())
-      .WillByDefault(Return(content::DOWNLOAD_INTERRUPT_REASON_NONE));
+  ON_CALL(*this, Initialize(_))
+      .WillByDefault(::testing::Invoke(SuccessRun));
 }
 
 MockDownloadFile::~MockDownloadFile() {
 }