Reland: Lazily initialize MessageLoop for faster thread startup

chrome/browser/metrics/thread_watcher_android_unittest.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 "base/android/application_status_listener.h"
 #include "base/run_loop.h"
 #include "base/synchronization/waitable_event.h"
 #include "chrome/browser/metrics/thread_watcher.h"
 #include "chrome/browser/metrics/thread_watcher_android.h"
@@ skipping 30 matching lines @@
 // This test is flaky: http://crbug.com/485091.
 TEST(ThreadWatcherAndroidTest, DISABLED_ApplicationStatusNotification) {
   // Do not delay the ThreadWatcherList initialization for this test.
   ThreadWatcherList::g_initialize_delay_seconds = 0;
 
   base::MessageLoopForUI message_loop_for_ui;
   content::TestBrowserThread ui_thread(BrowserThread::UI, &message_loop_for_ui);
 
 
   scoped_ptr<WatchDogThread> watchdog_thread_(new WatchDogThread());
-  watchdog_thread_->Start();
+  watchdog_thread_->StartAndWaitForTesting();
 
   EXPECT_FALSE(ThreadWatcherList::g_thread_watcher_list_);
 
 
   // Register, and notify the application has just started,
   // and ensure the thread watcher list is created.
   ThreadWatcherAndroid::RegisterApplicationStatusListener();
   ThreadWatcherList::StartWatchingAll(*base::CommandLine::ForCurrentProcess());
   NotifyApplicationStateChange(
       base::android::APPLICATION_STATE_HAS_RUNNING_ACTIVITIES);
   EXPECT_TRUE(ThreadWatcherList::g_thread_watcher_list_);
 
   // Notify the application has been stopped, and ensure the thread watcher list
   // has been destroyed.
   NotifyApplicationStateChange(
       base::android::APPLICATION_STATE_HAS_STOPPED_ACTIVITIES);
   EXPECT_FALSE(ThreadWatcherList::g_thread_watcher_list_);
 
   // And again the last transition, STOPPED -> STARTED.
   NotifyApplicationStateChange(
       base::android::APPLICATION_STATE_HAS_RUNNING_ACTIVITIES);
   EXPECT_TRUE(ThreadWatcherList::g_thread_watcher_list_);
 }