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

content/browser/renderer_host/media/audio_output_device_enumerator.cc

 // Copyright (c) 2015 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 "content/browser/renderer_host/media/audio_output_device_enumerator.h"
 
 #include "base/callback_helpers.h"
 #include "base/location.h"
 #include "base/single_thread_task_runner.h"
 #include "base/task_runner_util.h"
 #include "base/thread_task_runner_handle.h"
 #include "media/audio/audio_manager_base.h"
 
 namespace content {
 
 namespace {
 
 AudioOutputDeviceEnumeration EnumerateDevicesOnDeviceThread(
     media::AudioManager* audio_manager) {
   DCHECK(audio_manager->GetWorkerTaskRunner()->BelongsToCurrentThread());
 
   AudioOutputDeviceEnumeration snapshot;
   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()
              : audio_manager->GetOutputStreamParameters(name.unique_id)});
   }
   return snapshot;
 }
 
 }  // 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)
     : audio_manager_(audio_manager),
       cache_policy_(cache_policy),
       current_event_sequence_(0),
       seq_last_enumeration_(0),
       seq_last_invalidation_(0),
       is_enumeration_ongoing_(false),
       weak_factory_(this) {}
@@ skipping 74 matching lines @@
   return ++current_event_sequence_;
 }
 
 bool AudioOutputDeviceEnumerator::IsLastEnumerationValid() const {
   DCHECK(thread_checker_.CalledOnValidThread());
   return seq_last_enumeration_ > seq_last_invalidation_ &&
          !is_enumeration_ongoing_;
 }
 
 }  // namespace content