Lazily initialize MessageLoop for faster thread startup

sandbox/linux/services/thread_helpers_unittests.cc

Index: sandbox/linux/services/thread_helpers_unittests.cc
diff --git a/sandbox/linux/services/thread_helpers_unittests.cc b/sandbox/linux/services/thread_helpers_unittests.cc
index 888651671d55f2cc17d457b362f22f8f715c4dda..f64fee2f792a036f2244dccee1bfa98a6e6ee291 100644
--- a/sandbox/linux/services/thread_helpers_unittests.cc
+++ b/sandbox/linux/services/thread_helpers_unittests.cc
@@ -98,7 +98,7 @@ TEST(ThreadHelpers, IsSingleThreadedStartAndStop) {
   // This is testing for a race condition, so iterate.
   // Manually, this has been tested with more that 1M iterations.
   for (int i = 0; i < GetRaceTestIterations(); ++i) {
-    ASSERT_TRUE(thread.Start());
+    ASSERT_TRUE(thread.StartAndWait());
     ASSERT_FALSE(ThreadHelpers::IsSingleThreaded(proc_fd.fd()));
 
     ASSERT_TRUE(ThreadHelpers::StopThreadAndWatchProcFS(proc_fd.fd(), &thread));