Add empty Linux implementation of audio_service.

chrome/chrome_browser_extensions.gypi

 # Copyright (c) 2013 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.
 
 {
   'targets': [
     {
       'target_name': 'browser_extensions',
       'type': 'static_library',
       'variables': { 'enable_wexit_time_destructors': 1, },
@@ skipping 118 matching lines @@
         'browser/extensions/api/alarms/alarm_manager.cc',
         'browser/extensions/api/alarms/alarm_manager.h',
         'browser/extensions/api/alarms/alarms_api.cc',
         'browser/extensions/api/alarms/alarms_api.h',
         'browser/extensions/api/app_current_window_internal/app_current_window_internal_api.cc',
         'browser/extensions/api/app_current_window_internal/app_current_window_internal_api.h',
         'browser/extensions/api/app_window/app_window_api.cc',
         'browser/extensions/api/app_window/app_window_api.h',
         'browser/extensions/api/audio/audio_api.cc',
         'browser/extensions/api/audio/audio_api.h',
         'browser/extensions/api/audio/audio_service.cc',

[Lei Zhang, 2014/07/01 05:37:25]

You forgot to exclude this, so the dummy implementation here gets built as well
and used. When I simply changed the ordering, the new Linux AudioServiceImpl
gets used and fails. I've fixed this in
https://codereview.chromium.org/354303003

         'browser/extensions/api/audio/audio_service.h',
         'browser/extensions/api/audio/audio_service_chromeos.cc',
+        'browser/extensions/api/audio/audio_service_linux.cc',
         'browser/extensions/api/automation_internal/automation_internal_api.cc',
         'browser/extensions/api/automation_internal/automation_internal_api.h',
         'browser/extensions/api/automation_internal/automation_util.cc',
         'browser/extensions/api/automation_internal/automation_util.h',
         'browser/extensions/api/autotest_private/autotest_private_api.cc',
         'browser/extensions/api/autotest_private/autotest_private_api.h',
         'browser/extensions/api/bluetooth/bluetooth_api.cc',
         'browser/extensions/api/bluetooth/bluetooth_api.h',
         'browser/extensions/api/bluetooth/bluetooth_api_pairing_delegate.cc',
         'browser/extensions/api/bluetooth/bluetooth_api_pairing_delegate.h',
@@ skipping 1062 matching lines @@
       'type': 'static_library',
       'sources': [ 'browser/extensions/api/cast_channel/cast_channel.proto' ],
       'variables': {
           'proto_in_dir': 'browser/extensions/api/cast_channel',
           'proto_out_dir': 'chrome/browser/extensions/api/cast_channel',
       },
       'includes': [ '../build/protoc.gypi' ]
     },
   ],  # 'conditions'
 }