Introduce background Download process to android

content/content_app.gypi

 # 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_dirs': [
     '..',
   ],
   'dependencies': [
     '../base/base.gyp:base',
     '../base/base.gyp:base_i18n',
     '../crypto/crypto.gyp:crypto',
     '../mojo/mojo_base.gyp:mojo_environment_chromium',
     '../third_party/mojo/mojo_edk.gyp:mojo_system_impl',
     '../ui/base/ui_base.gyp:ui_base',
     '../ui/gfx/gfx.gyp:gfx',
     '../ui/gfx/gfx.gyp:gfx_geometry',
     'content_common_mojo_bindings.gyp:content_common_mojo_bindings',
   ],
   'sources': [
     'app/android/app_jni_registrar.cc',
     'app/android/app_jni_registrar.h',
     'app/android/child_process_service.cc',
     'app/android/child_process_service.h',
     'app/android/content_jni_onload.cc',
     'app/android/content_main.cc',
     'app/android/content_main.h',
+    'app/android/download_main.cc',
     'app/android/library_loader_hooks.cc',
     'app/android/library_loader_hooks.h',
     'app/content_main.cc',
     'app/content_main_runner.cc',
     'app/mac/mac_init.mm',
     'app/mac/mac_init.h',
     'app/mojo/mojo_init.cc',
     'app/mojo/mojo_init.h',
     'public/app/content_jni_onload.h',
     'public/app/content_main.h',
@@ skipping 13 matching lines @@
         '../ui/android/ui_android.gyp:ui_android',
       ],
     }],
     ['OS=="win"', {
       'dependencies': [
         'content.gyp:sandbox_helper_win',
       ],
     }],
   ],
 }