Clean up PlatformThread.

webrtc/modules/audio_device/mac/audio_device_mac.cc

Index: webrtc/modules/audio_device/mac/audio_device_mac.cc
diff --git a/webrtc/modules/audio_device/mac/audio_device_mac.cc b/webrtc/modules/audio_device/mac/audio_device_mac.cc
index 14e6bbdfbb63ebea71f335f5786e8be7ce83166b..3449188dc0c9bf9b90b9a285ab44e6b675a18def 100644
--- a/webrtc/modules/audio_device/mac/audio_device_mac.cc
+++ b/webrtc/modules/audio_device/mac/audio_device_mac.cc
@@ -1665,11 +1665,11 @@ int32_t AudioDeviceMac::StartRecording()
     }
 
     RTC_DCHECK(!capture_worker_thread_.get());
-    capture_worker_thread_ =
-        PlatformThread::CreateThread(RunCapture, this, "CaptureWorkerThread");
+    capture_worker_thread_.reset(
+        new rtc::PlatformThread(RunCapture, this, "CaptureWorkerThread"));
     RTC_DCHECK(capture_worker_thread_.get());
     capture_worker_thread_->Start();
-    capture_worker_thread_->SetPriority(kRealtimePriority);
+    capture_worker_thread_->SetPriority(rtc::kRealtimePriority);
 
     OSStatus err = noErr;
     if (_twoDevices)
@@ -1820,10 +1820,10 @@ int32_t AudioDeviceMac::StartPlayout()
     }
 
     RTC_DCHECK(!render_worker_thread_.get());
-    render_worker_thread_ =
-        PlatformThread::CreateThread(RunRender, this, "RenderWorkerThread");
+    render_worker_thread_.reset(
+        new rtc::PlatformThread(RunRender, this, "RenderWorkerThread"));
     render_worker_thread_->Start();
-    render_worker_thread_->SetPriority(kRealtimePriority);
+    render_worker_thread_->SetPriority(rtc::kRealtimePriority);
 
     if (_twoDevices || !_recording)
     {