Automated IWYU fix for TaskRunner includes.

components/invalidation/impl/unacked_invalidation_set_unittest.cc

 // Copyright 2014 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/invalidation/impl/unacked_invalidation_set.h"
 
 #include <stddef.h>
 
 #include <memory>
 
 #include "base/json/json_string_value_serializer.h"
+#include "base/single_thread_task_runner.h"
 #include "base/strings/string_number_conversions.h"
 #include "components/invalidation/impl/unacked_invalidation_set_test_util.h"
 #include "components/invalidation/public/object_id_invalidation_map.h"
 #include "components/invalidation/public/single_object_invalidation_set.h"
 #include "testing/gtest/include/gtest/gtest.h"
 
 namespace syncer {
 
 class UnackedInvalidationSetTest : public testing::Test {
  public:
@@ skipping 233 matching lines @@
   bool result = UnackedInvalidationSet::DeserializeSetIntoMap(dict, &map);
   EXPECT_TRUE(result);
   auto item = map.find(kObjectId_);
   ASSERT_NE(map.end(), item);
   EXPECT_EQ(kObjectId_, item->second.object_id());
 }
 
 }  // namespace
 
 }  // namespace syncer