Automated IWYU fix for TaskRunner includes.

components/wallpaper/wallpaper_color_calculator_unittest.cc

 // Copyright 2017 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/wallpaper/wallpaper_color_calculator.h"
 
 #include <memory>
 
 #include "base/macros.h"
 #include "base/memory/ptr_util.h"
+#include "base/single_thread_task_runner.h"
 #include "base/test/histogram_tester.h"
 #include "base/test/null_task_runner.h"
 #include "base/test/test_mock_time_task_runner.h"
 #include "base/threading/thread_task_runner_handle.h"
 #include "components/wallpaper/wallpaper_color_calculator_observer.h"
 #include "skia/ext/platform_canvas.h"
 #include "testing/gtest/include/gtest/gtest.h"
 #include "third_party/skia/include/core/SkBitmap.h"
 #include "third_party/skia/include/core/SkColor.h"
 #include "ui/gfx/canvas.h"
@@ skipping 209 matching lines @@
 
   EXPECT_TRUE(calculator_->StartCalculation());
 
   histograms_.ExpectUniqueSample("Ash.Wallpaper.ColorExtractionResult", false,
                                  1);
   histograms_.ExpectTotalCount("Ash.Wallpaper.ColorExtraction.Durations", 1);
   histograms_.ExpectTotalCount("Ash.Wallpaper.ColorExtraction.UserDelay", 0);
 }
 
 }  // namespace wallpaper