Lazily initialize MessageLoop for faster thread startup

sandbox/linux/services/thread_helpers_unittests.cc

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "sandbox/linux/services/thread_helpers.h"
 
 #include <errno.h>
 #include <fcntl.h>
 #include <sys/stat.h>
 #include <sys/types.h>
@@ skipping 80 matching lines @@
 }
 
 TEST(ThreadHelpers, IsSingleThreadedStartAndStop) {
   ScopedProc proc_fd;
   ASSERT_TRUE(ThreadHelpers::IsSingleThreaded(proc_fd.fd()));
 
   base::Thread thread("sandbox_tests");
   // 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));
     ASSERT_TRUE(ThreadHelpers::IsSingleThreaded(proc_fd.fd()));
     ASSERT_EQ(1, base::GetNumberOfThreads(base::GetCurrentProcessHandle()));
   }
 }
 
 SANDBOX_TEST(ThreadHelpers, AssertSingleThreadedAfterThreadStopped) {
   SANDBOX_ASSERT(ThreadHelpers::IsSingleThreaded());
@@ skipping 27 matching lines @@
   SANDBOX_ASSERT(thread1.Start());
   ThreadHelpers::AssertSingleThreaded();
 }
 #endif  // !defined(NDEBUG)
 
 #endif  // !defined(THREAD_SANITIZER)
 
 }  // namespace
 
 }  // namespace sandbox