Add task runners to more tests

media/video/capture/mac/video_capture_device_factory_mac_unittest.mm

Index: media/video/capture/mac/video_capture_device_factory_mac_unittest.mm
diff --git a/media/video/capture/mac/video_capture_device_factory_mac_unittest.mm b/media/video/capture/mac/video_capture_device_factory_mac_unittest.mm
index 7094f3dd57c4183bdf75656c6afd6a0944bd759c..ee7b8803c923e4d99d07161915679e3ef4cc0e86 100644
--- a/media/video/capture/mac/video_capture_device_factory_mac_unittest.mm
+++ b/media/video/capture/mac/video_capture_device_factory_mac_unittest.mm
@@ -3,7 +3,7 @@
 // found in the LICENSE file.
 
 #include "base/command_line.h"
-#include "base/message_loop/message_loop_proxy.h"
+#include "base/message_loop/message_loop.h"
 #import "media/base/mac/avfoundation_glue.h"
 #include "media/base/media_switches.h"
 #include "media/video/capture/mac/video_capture_device_factory_mac.h"
@@ -17,6 +17,9 @@ class VideoCaptureDeviceFactoryMacTest : public testing::Test {
     base::CommandLine::ForCurrentProcess()->AppendSwitch(
         switches::kEnableAVFoundation);
   }
+
+ private:
+  base::MessageLoop message_loop_;
 };
 
 TEST_F(VideoCaptureDeviceFactoryMacTest, ListDevicesAVFoundation) {