Get rid of virtual Display::CreateScheduler.

base/test/test_message_loop.h

Index: base/test/test_message_loop.h
diff --git a/base/test/test_message_loop.h b/base/test/test_message_loop.h
index fbb06694d4750408cabb31a2a6410c57bb103078..9c0aed8b8b068cbbf412c9cc5c66d43d33b8db8a 100644
--- a/base/test/test_message_loop.h
+++ b/base/test/test_message_loop.h
@@ -21,6 +21,10 @@ class TestMessageLoop {
   explicit TestMessageLoop(MessageLoop::Type type);
   ~TestMessageLoop();
 
+  const scoped_refptr<SingleThreadTaskRunner>& task_runner() {
+    return loop_.task_runner();
+  }
+
  private:
   MessageLoop loop_;
 };