Remove implicit conversions from scoped_refptr to T* in media/

media/video/capture/mac/video_capture_device_factory_mac.mm

Index: media/video/capture/mac/video_capture_device_factory_mac.mm
diff --git a/media/video/capture/mac/video_capture_device_factory_mac.mm b/media/video/capture/mac/video_capture_device_factory_mac.mm
index 8440ec4d9e1820f919e4c278546b344f66fa2729..f383b425fde3c4169bee5a3503074ef98a0f7c82 100644
--- a/media/video/capture/mac/video_capture_device_factory_mac.mm
+++ b/media/video/capture/mac/video_capture_device_factory_mac.mm
@@ -173,7 +173,9 @@ void VideoCaptureDeviceFactoryMac::EnumerateDeviceNames(const base::Callback<
     callback.Run(device_names.Pass());
   } else {
     DVLOG(1) << "Enumerating video capture devices using QTKit";
-    base::PostTaskAndReplyWithResult(ui_task_runner_, FROM_HERE,
+    base::PostTaskAndReplyWithResult(
+        ui_task_runner_.get(),
+        FROM_HERE,
         base::Bind(&EnumerateDevicesUsingQTKit),
         base::Bind(&RunDevicesEnumeratedCallback, callback));
   }