Revert of Reland: Lazily initialize MessageLoop for faster thread startup

base/threading/thread_unittest.cc

 // Copyright (c) 2012 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 "base/threading/thread.h"
 
 #include <vector>
 
 #include "base/bind.h"
 #include "base/location.h"
@@ skipping 176 matching lines @@
   EXPECT_FALSE(a.message_loop());
   EXPECT_FALSE(a.IsRunning());
 }
 
 TEST_F(ThreadTest, ThreadName) {
   Thread a("ThreadName");
   EXPECT_TRUE(a.Start());
   EXPECT_EQ("ThreadName", a.thread_name());
 }
 
-// Make sure Init() is called after Start() and before
-// WaitUntilThreadInitialized() returns.
+// Make sure we can't use a thread between Start() and Init().
 TEST_F(ThreadTest, SleepInsideInit) {
   SleepInsideInitThread t;
   EXPECT_FALSE(t.InitCalled());
-  t.StartAndWaitForTesting();
+  t.Start();
   EXPECT_TRUE(t.InitCalled());
 }
 
 // Make sure that the destruction sequence is:
 //
 //  (1) Thread::CleanUp()
 //  (2) MessageLoop::~MessageLoop()
 //      MessageLoop::DestructionObservers called.
 TEST_F(ThreadTest, CleanUp) {
   EventList captured_events;
@@ skipping 14 matching lines @@
 
     // Upon leaving this scope, the thread is deleted.
   }
 
   // Check the order of events during shutdown.
   ASSERT_EQ(static_cast<size_t>(THREAD_NUM_EVENTS), captured_events.size());
   EXPECT_EQ(THREAD_EVENT_INIT, captured_events[0]);
   EXPECT_EQ(THREAD_EVENT_CLEANUP, captured_events[1]);
   EXPECT_EQ(THREAD_EVENT_MESSAGE_LOOP_DESTROYED, captured_events[2]);
 }