Correctly handle enumerations for AudioManagers that report only the default audio output device.

content/browser/renderer_host/media/media_stream_manager.cc

Index: content/browser/renderer_host/media/media_stream_manager.cc
diff --git a/content/browser/renderer_host/media/media_stream_manager.cc b/content/browser/renderer_host/media/media_stream_manager.cc
index 49c828b00ecebe32dbbb583c936f87e3dcc45c8d..f602e8d26b18da9875b53e46862955751067afd3 100644
--- a/content/browser/renderer_host/media/media_stream_manager.cc
+++ b/content/browser/renderer_host/media/media_stream_manager.cc
@@ -739,10 +739,8 @@ void MediaStreamManager::AudioOutputDevicesEnumerated(
   DVLOG(1) << "AudioOutputDevicesEnumerated()";
   StreamDeviceInfoArray device_infos;
 
-  // If the enumeration contains only one entry, it means there are no devices.
-  // The single entry contains default parameters from the audio manager.
-  if (device_enumeration.size() > 1) {

[tommi (sloooow) - chröme, 2016/01/19 13:03:37]

instead of the 'has_actual_devices' member variable, could we have a method like
so:

bool has_actual_devices() const {
  // <include comment>
  return devices.size() > 1;
}

?

[Guido Urdaneta, 2016/01/19 13:41:10]

devices.size() > 1 is incorrect for AudioManagers that always report only one
device.
The has_actual_devices field allows differentiating that from the case where
there are no devices (but where we have one entry with the default parameters).
I updated the AudioOutputDeviceEnumerator::Enumerate() comment to explain that.

-    for (const auto& entry : device_enumeration) {
+  if (device_enumeration.has_actual_devices) {
+    for (const auto& entry : device_enumeration.devices) {
       StreamDeviceInfo device_info(MEDIA_DEVICE_AUDIO_OUTPUT, entry.device_name,
                                    entry.unique_id);
       device_infos.push_back(device_info);