Add AshDesktopMediaList and enable Desktop Capture API on Chrome OS.

ui/snapshot/snapshot.gyp

 # 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.
 
 {
   'variables': {
     'chromium_code': 1,
   },
   'targets': [
     {
@@ skipping 19 matching lines @@
         'snapshot_mac.mm',
         'snapshot_win.cc',
         'snapshot_win.h',
       ],
       'include_dirs': [
         '..',
       ],
       'conditions': [
         ['use_aura==1', {
           'dependencies': [
+            '../../cc/cc.gyp:cc',
             '../aura/aura.gyp:aura',
             '../compositor/compositor.gyp:compositor',
           ],
         }],
       ],
     },
     {
       'target_name': 'snapshot_unittests',
       'type': '<(gtest_target_type)',
       'dependencies': [
@@ skipping 43 matching lines @@
             'snapshot',
           ],
           'include_dirs': [
             '../..',
           ],
         },
       ],
     }],
   ],
 }