Rewrite DownloadHandlerTest using DummyFileSystem.

chrome/browser/chromeos/drive/mock_file_system.cc

Index: chrome/browser/chromeos/drive/mock_file_system.cc
diff --git a/chrome/browser/chromeos/drive/mock_file_system.cc b/chrome/browser/chromeos/drive/mock_file_system.cc
deleted file mode 100644
index 02f9b7ba2bd848827e68315cf951f614258569f1..0000000000000000000000000000000000000000
--- a/chrome/browser/chromeos/drive/mock_file_system.cc
+++ /dev/null
@@ -1,15 +0,0 @@
-// 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 "chrome/browser/chromeos/drive/mock_file_system.h"
-
-namespace drive {
-
-MockFileSystem::MockFileSystem() {
-}
-
-MockFileSystem::~MockFileSystem() {
-}
-
-}  // namespace drive