Add base::RunLoop and update ui_test_utils to use it to reduce flakiness

base/message_loop.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/message_loop.h"
 
 #include <algorithm>
 
 #include "base/bind.h"
 #include "base/compiler_specific.h"
@@ skipping 317 matching lines @@
     pump_->Quit();
   } else {
     NOTREACHED() << "Must be inside Run to call Quit";
   }
 }
 
 static void QuitCurrent() {
   MessageLoop::current()->Quit();
 }
 
+static void QuitNowCurrent() {
+  MessageLoop::current()->QuitNow();
+}
+
 // static
 base::Closure MessageLoop::QuitClosure() {
   return base::Bind(&QuitCurrent);
 }
 
+// static
+base::Closure MessageLoop::QuitNowClosure() {
+  return base::Bind(&QuitNowCurrent);
+}
+
 void MessageLoop::SetNestableTasksAllowed(bool allowed) {
   if (nestable_tasks_allowed_ != allowed) {
     nestable_tasks_allowed_ = allowed;
     if (!nestable_tasks_allowed_)
       return;
     // Start the native pump if we are not already pumping.
     pump_->ScheduleWork();
   }
 }
 
@@ skipping 448 matching lines @@
                                            Watcher *delegate) {
   return pump_libevent()->WatchFileDescriptor(
       fd,
       persistent,
       static_cast<base::MessagePumpLibevent::Mode>(mode),
       controller,
       delegate);
 }
 
 #endif