Remove calls to deprecated MessageLoop methods in components/previews/.

components/previews/previews_io_data_unittest.cc

 // 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.
 
 #include "components/previews/previews_io_data.h"
 
 #include <memory>
 
 #include "base/memory/ptr_util.h"
 #include "base/memory/ref_counted.h"
 #include "base/message_loop/message_loop.h"
+#include "base/run_loop.h"
 #include "base/single_thread_task_runner.h"
 #include "components/previews/previews_ui_service.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
 namespace previews {
 
 namespace {
 
 class TestPreviewsIOData : public PreviewsIOData {
  public:
@@ skipping 42 matching lines @@
   std::unique_ptr<PreviewsUIService> ui_service_;
 };
 
 }  // namespace
 
 TEST_F(PreviewsIODataTest, TestInitialization) {
   set_io_data(base::WrapUnique(
       new TestPreviewsIOData(loop_.task_runner(), loop_.task_runner())));
   set_ui_service(
       base::WrapUnique(new PreviewsUIService(io_data(), loop_.task_runner())));
-  loop_.RunUntilIdle();
+  base::RunLoop().RunUntilIdle();
   // After the outstanding posted tasks have run, |io_data_| should be fully
   // initialized.
   EXPECT_TRUE(io_data()->initialized());
 }
 
 }  // namespace previews