Don't build a bunch of stuff on Aura, rather than ifdefing out code in it.

chrome/browser/plugin_download_helper.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 "chrome/browser/plugin_download_helper.h"
 
-#if defined(OS_WIN) && !defined(USE_AURA)
 #include <windows.h>
 
 #include "base/file_util.h"
 #include "content/public/browser/browser_thread.h"
 #include "content/public/common/url_fetcher.h"
 #include "net/base/io_buffer.h"
 
 PluginDownloadUrlHelper::PluginDownloadUrlHelper(
     const std::string& download_url,
     gfx::NativeWindow caller_window,
@@ skipping 57 matching lines @@
 
     if (::IsWindow(download_file_caller_window_)) {
       ::SendMessage(download_file_caller_window_, WM_COPYDATA, NULL,
                     reinterpret_cast<LPARAM>(&download_file_data));
     }
   }
   // Don't access any members after this.
   delete this;
 }
 
-#endif  // defined(OS_WIN) && !defined(USE_AURA)