Revert of Do not block in SimpleThread::Start().

base/threading/simple_thread_unittest.cc

Index: base/threading/simple_thread_unittest.cc
diff --git a/base/threading/simple_thread_unittest.cc b/base/threading/simple_thread_unittest.cc
index 969418b219a6fda80d03965630ed292c9a770b8e..0e52500c522d7d84b6bebc6f69c9d2ad1e7289c6 100644
--- a/base/threading/simple_thread_unittest.cc
+++ b/base/threading/simple_thread_unittest.cc
@@ -129,11 +129,17 @@
   EXPECT_EQ(0, stack_int);
 
   DelegateSimpleThread thread(&runner, "int_setter");
+  EXPECT_FALSE(thread.HasBeenStarted());
+  EXPECT_FALSE(thread.HasBeenJoined());
   EXPECT_EQ(0, stack_int);
 
   thread.Start();
+  EXPECT_TRUE(thread.HasBeenStarted());
+  EXPECT_FALSE(thread.HasBeenJoined());
+
   thread.Join();
-
+  EXPECT_TRUE(thread.HasBeenStarted());
+  EXPECT_TRUE(thread.HasBeenJoined());
   EXPECT_EQ(7, stack_int);
 }
 
@@ -159,11 +165,16 @@
   options.joinable = false;
   DelegateSimpleThread thread(&runner, "non_joinable", options);
 
+  EXPECT_FALSE(thread.HasBeenStarted());
   thread.Start();
-
-  // Wait until Run() is invoked.
+  EXPECT_TRUE(thread.HasBeenStarted());
+
+  // Note: this is not quite the same as |thread.HasBeenStarted()| which
+  // represents ThreadMain() getting ready to invoke Run() whereas
+  // |runner.WaitUntilStarted()| ensures Run() was actually invoked.
   runner.WaitUntilStarted();
 
+  EXPECT_FALSE(thread.HasBeenJoined());
   EXPECT_DCHECK_DEATH({ thread.Join(); });
 }