Mac AVFoundation: Enumerate devices in device/audio thread. Take 2.

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 1155f69aadadb1834ce9d04d011b994f29df5355..049e56fa65d0adadb25f25f497166878f1d5b84b 100644
--- a/content/browser/renderer_host/media/media_stream_manager.cc
+++ b/content/browser/renderer_host/media/media_stream_manager.cc
@@ -50,7 +50,8 @@ namespace content {
 // Forward declaration of DeviceMonitorMac and its only useable method.
 class DeviceMonitorMac {
  public:
-  void StartMonitoring();
+  void StartMonitoring(
+    const scoped_refptr<base::SingleThreadTaskRunner>& device_task_runner);
 };
 
 namespace {
@@ -837,8 +838,10 @@ void MediaStreamManager::StartMonitoring() {
 void MediaStreamManager::StartMonitoringOnUIThread() {
   DCHECK_CURRENTLY_ON(BrowserThread::UI);
   BrowserMainLoop* browser_main_loop = content::BrowserMainLoop::GetInstance();
-  if (browser_main_loop)
-    browser_main_loop->device_monitor_mac()->StartMonitoring();
+  if (browser_main_loop) {
+    browser_main_loop->device_monitor_mac()
+        ->StartMonitoring(audio_manager_->GetWorkerTaskRunner());
+  }
 }
 #endif