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

content/browser/renderer_host/media/audio_output_device_enumerator.cc

Index: content/browser/renderer_host/media/audio_output_device_enumerator.cc
diff --git a/content/browser/renderer_host/media/audio_output_device_enumerator.cc b/content/browser/renderer_host/media/audio_output_device_enumerator.cc
index 70a432065ce0df10c240b57049046ad2bd2bf125..54c05311e1fafbaa5a801a34559831cea738d2b7 100644
--- a/content/browser/renderer_host/media/audio_output_device_enumerator.cc
+++ b/content/browser/renderer_host/media/audio_output_device_enumerator.cc
@@ -23,16 +23,19 @@ AudioOutputDeviceEnumeration EnumerateDevicesOnDeviceThread(
   media::AudioDeviceNames device_names;
   audio_manager->GetAudioOutputDeviceNames(&device_names);
 
+  snapshot.has_actual_devices = !device_names.empty();
+
   // If no devices in enumeration, return a list with a default device
-  if (device_names.empty()) {
-    snapshot.push_back({media::AudioManagerBase::kDefaultDeviceId,
-                        media::AudioManager::GetDefaultDeviceName(),
-                        audio_manager->GetDefaultOutputStreamParameters()});
+  if (!snapshot.has_actual_devices) {
+    snapshot.devices.push_back(
+        {media::AudioManagerBase::kDefaultDeviceId,
+         media::AudioManager::GetDefaultDeviceName(),
+         audio_manager->GetDefaultOutputStreamParameters()});
     return snapshot;
   }
 
   for (const media::AudioDeviceName& name : device_names) {
-    snapshot.push_back(
+    snapshot.devices.push_back(
         {name.unique_id, name.device_name,
          name.unique_id == media::AudioManagerBase::kDefaultDeviceId
              ? audio_manager->GetDefaultOutputStreamParameters()
@@ -43,6 +46,16 @@ AudioOutputDeviceEnumeration EnumerateDevicesOnDeviceThread(
 
 }  // namespace
 
+AudioOutputDeviceEnumeration::AudioOutputDeviceEnumeration(
+    const std::vector<AudioOutputDeviceInfo>& devices,
+    bool has_actual_devices)
+    : devices(devices), has_actual_devices(has_actual_devices) {}
+
+AudioOutputDeviceEnumeration::AudioOutputDeviceEnumeration()
+    : has_actual_devices(false) {}
+
+AudioOutputDeviceEnumeration::~AudioOutputDeviceEnumeration() {}
+
 AudioOutputDeviceEnumerator::AudioOutputDeviceEnumerator(
     media::AudioManager* audio_manager,
     CachePolicy cache_policy)