Expose stable_device_id in audio extension apis.

extensions/browser/api/audio/audio_service_chromeos.cc

 // 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.
 
 #include "extensions/browser/api/audio/audio_service.h"
 
 #include <stddef.h>
 #include <stdint.h>
 
 #include "base/callback.h"
@@ skipping 255 matching lines @@
     info->is_active = devices[i].active;
     info->is_muted =
         devices[i].is_input
             ? cras_audio_handler_->IsInputMutedForDevice(devices[i].id)
             : cras_audio_handler_->IsOutputMutedForDevice(devices[i].id);
     info->level =
         devices[i].is_input
             ? cras_audio_handler_->GetOutputVolumePercentForDevice(
                   devices[i].id)
             : cras_audio_handler_->GetInputGainPercentForDevice(devices[i].id);
-    // TODO(jennyz): Set stable_device_id once it is implemented.
-    // See crbug.com/466768.
+    info->stable_device_id.reset(
+        new std::string(base::Uint64ToString(devices[i].stable_device_id)));
 
     devices_info_list.push_back(info);
   }
 
   FOR_EACH_OBSERVER(AudioService::Observer, observer_list_,
                     OnDevicesChanged(devices_info_list));
 
   // Notify DeviceChanged event for backward compatibility.
   // TODO(jennyz): remove this code when the old version of hotrod retires.
   NotifyDeviceChanged();
 }
 
 AudioService* AudioService::CreateInstance() {
   return new AudioServiceImpl;
 }
 
 }  // namespace extensions