Get rid of virtual Display::CreateScheduler.

base/test/test_message_loop.h

 // Copyright 2016 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.
 
 #ifndef BASE_TEST_TEST_MESSAGE_LOOP_H_
 #define BASE_TEST_TEST_MESSAGE_LOOP_H_
 
 #include "base/message_loop/message_loop.h"
 
 namespace base {
 
 // TestMessageLoop is a convenience class for unittests that need to create a
 // message loop without a real thread backing it. For most tests,
 // it is sufficient to just instantiate TestMessageLoop as a member variable.
 //
 // TestMessageLoop will attempt to drain the underlying MessageLoop on
 // destruction for clean teardown of tests.
 class TestMessageLoop {
  public:
   TestMessageLoop();
   explicit TestMessageLoop(MessageLoop::Type type);
   ~TestMessageLoop();
 
+  const scoped_refptr<SingleThreadTaskRunner>& task_runner() {
+    return loop_.task_runner();
+  }
+
  private:
   MessageLoop loop_;
 };
 
 }  // namespace base
 
 #endif  // BASE_TEST_TEST_MESSAGE_LOOP_H_