Delete optional Runnable argument to rtc::Thread::Start

Intended to simplify later changes to thread shutdown logic.

Bug: webrtc:10648
Change-Id: I61ba240c0f4b73a0bc6af6a3471804ecb434c41f
Reviewed-on: https://webrtc-review.googlesource.com/c/src/+/137510
Commit-Queue: Niels Moller <nisse@webrtc.org>
Reviewed-by: Karl Wiberg <kwiberg@webrtc.org>
Cr-Commit-Position: refs/heads/master@{#28219}
diff --git a/rtc_base/physical_socket_server_unittest.cc b/rtc_base/physical_socket_server_unittest.cc
index 611fb18..3987a59 100644
--- a/rtc_base/physical_socket_server_unittest.cc
+++ b/rtc_base/physical_socket_server_unittest.cc
@@ -594,21 +594,6 @@
   EXPECT_TRUE(ExpectNone());
 }
 
-class RaiseSigTermRunnable : public Runnable {
-  void Run(Thread* thread) override {
-    thread->socketserver()->Wait(1000, false);
-
-    // Allow SIGTERM. This will be the only thread with it not masked so it will
-    // be delivered to us.
-    sigset_t mask;
-    sigemptyset(&mask);
-    pthread_sigmask(SIG_SETMASK, &mask, nullptr);
-
-    // Raise it.
-    raise(SIGTERM);
-  }
-};
-
 // Test that it works no matter what thread the kernel chooses to give the
 // signal to (since it's not guaranteed to be the one that Wait() runs on).
 // TODO(webrtc:7864): Fails on real iOS devices
@@ -628,8 +613,19 @@
   // thread. Our implementation should safely handle it and dispatch
   // RecordSignal() on this thread.
   std::unique_ptr<Thread> thread(Thread::CreateWithSocketServer());
-  std::unique_ptr<RaiseSigTermRunnable> runnable(new RaiseSigTermRunnable());
-  thread->Start(runnable.get());
+  thread->Start();
+  thread->PostTask(RTC_FROM_HERE, [&thread]() {
+    thread->socketserver()->Wait(1000, false);
+    // Allow SIGTERM. This will be the only thread with it not masked so it will
+    // be delivered to us.
+    sigset_t mask;
+    sigemptyset(&mask);
+    pthread_sigmask(SIG_SETMASK, &mask, nullptr);
+
+    // Raise it.
+    raise(SIGTERM);
+  });
+
   EXPECT_TRUE(ss_->Wait(1500, true));
   EXPECT_TRUE(ExpectSignal(SIGTERM));
   EXPECT_EQ(Thread::Current(), signaled_thread_);