Reland: Lazily initialize MessageLoop for faster thread startup

chrome/browser/metrics/thread_watcher_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 <math.h>
 
 #include "base/basictypes.h"
 #include "base/bind.h"
 #include "base/logging.h"
 #include "base/memory/scoped_ptr.h"
@@ skipping 239 matching lines @@
   CustomThreadWatcher* io_watcher_;
   CustomThreadWatcher* db_watcher_;
   ThreadWatcherList* thread_watcher_list_;
 
   ThreadWatcherTest()
       : setup_complete_(&lock_),
         initialized_(false) {
     db_thread_.reset(new content::TestBrowserThread(BrowserThread::DB));
     io_thread_.reset(new content::TestBrowserThread(BrowserThread::IO));
     watchdog_thread_.reset(new WatchDogThread());
-    db_thread_->Start();
-    io_thread_->Start();
-    watchdog_thread_->Start();
+    db_thread_->StartAndWaitForTesting();
+    io_thread_->StartAndWaitForTesting();
+    watchdog_thread_->StartAndWaitForTesting();
 
     WatchDogThread::PostTask(
         FROM_HERE,
         base::Bind(&ThreadWatcherTest::SetUpObjects, base::Unretained(this)));
 
     WaitForSetUp(TimeDelta::FromMinutes(1));
   }
 
   void SetUpObjects() {
     DCHECK(WatchDogThread::CurrentlyOnWatchDogThread());
@@ skipping 417 matching lines @@
   bool stopped_;
 };
 
 TEST_F(ThreadWatcherListTest, Restart) {
   ThreadWatcherList::g_initialize_delay_seconds = 1;
 
   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();
 
   // See http://crbug.com/347887.
   // StartWatchingAll() will PostDelayedTask to create g_thread_watcher_list_,
   // whilst StopWatchingAll() will just PostTask to destroy it.
   // Ensure that when Stop is called, Start will NOT create
   // g_thread_watcher_list_ later on.
   ThreadWatcherList::StartWatchingAll(*base::CommandLine::ForCurrentProcess());
   ThreadWatcherList::StopWatchingAll();
   message_loop_for_ui.PostDelayedTask(
       FROM_HERE,
@@ skipping 25 matching lines @@
       FROM_HERE,
       message_loop_for_ui.QuitClosure(),
       base::TimeDelta::FromSeconds(
           ThreadWatcherList::g_initialize_delay_seconds));
   message_loop_for_ui.Run();
 
   CheckState(false /* has_thread_watcher_list */,
              true /* stopped */,
              "Stopped");
 }