Adds current thread to yielders in SimulatedThread::SendTask.

Bug: webrtc:11255
Change-Id: Ib65b902b60b15f402fac51269c74ac46b56cabc5
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/166462
Commit-Queue: Sebastian Jansson <srte@webrtc.org>
Reviewed-by: Niels Moller <nisse@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#30304}

test/time_controller/simulated_thread.cc

diff --git a/test/time_controller/simulated_thread.cc b/test/time_controller/simulated_thread.cc
index 8d82ebd..937fe32 100644
--- a/test/time_controller/simulated_thread.cc
+++ b/test/time_controller/simulated_thread.cc
@@ -81,8 +81,11 @@
   if (IsCurrent()) {
     msg.phandler->OnMessage(&msg);
   } else {
+    TaskQueueBase* yielding_from = TaskQueueBase::Current();
+    handler_->StartYield(yielding_from);
     CurrentThreadSetter set_current(this);
     msg.phandler->OnMessage(&msg);
+    handler_->StopYield(yielding_from);
   }
 }