Use SingleThreadedTaskQueue in DirectTransport

webrtc/test/BUILD.gn

Index: webrtc/test/BUILD.gn
diff --git a/webrtc/test/BUILD.gn b/webrtc/test/BUILD.gn
index 2db6120189aaa8c9fea4311a1e4f7301b18686d3..d1127d95dabca1d5fd5cdc1cf16c3e7b5e0a2dfc 100644
--- a/webrtc/test/BUILD.gn
+++ b/webrtc/test/BUILD.gn
@@ -287,6 +287,7 @@ if (!build_with_chromium) {
       "frame_generator_unittest.cc",
       "rtp_file_reader_unittest.cc",
       "rtp_file_writer_unittest.cc",
+      "single_threaded_task_queue_unittest.cc",
       "testsupport/always_passing_unittest.cc",
       "testsupport/metrics/video_metrics_unittest.cc",
       "testsupport/packet_reader_unittest.cc",
@@ -403,6 +404,20 @@ rtc_source_set("direct_transport") {
     "../rtc_base:rtc_base_approved",
     "../system_wrappers",
   ]
+  public_deps = [
+    ":single_threaded_task_queue",
+  ]
+}
+
+rtc_source_set("single_threaded_task_queue") {
+  testonly = true
+  sources = [
+    "single_threaded_task_queue.cc",
+    "single_threaded_task_queue.h",
+  ]
+  deps = [
+    "../rtc_base:rtc_base_approved",
+  ]
 }
 
 rtc_source_set("fake_audio_device") {