Automated IWYU fix for TaskRunner includes.

components/invalidation/impl/invalidation_notifier.h

 // 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.
 //
 // An implementation of Invalidator that wraps an invalidation
 // client.  Handles the details of connecting to XMPP and hooking it
 // up to the invalidation client.
 //
 // You probably don't want to use this directly; use
 // NonBlockingInvalidator.
 
 #ifndef COMPONENTS_INVALIDATION_IMPL_INVALIDATION_NOTIFIER_H_
 #define COMPONENTS_INVALIDATION_IMPL_INVALIDATION_NOTIFIER_H_
 
 #include <memory>
 #include <string>
 
 #include "base/compiler_specific.h"
 #include "base/macros.h"
 #include "base/memory/ref_counted.h"
 #include "base/memory/weak_ptr.h"
 #include "base/sequenced_task_runner.h"
+#include "base/single_thread_task_runner.h"
 #include "base/threading/non_thread_safe.h"
 #include "components/invalidation/impl/invalidation_state_tracker.h"
 #include "components/invalidation/impl/invalidator.h"
 #include "components/invalidation/impl/invalidator_registrar.h"
 #include "components/invalidation/impl/sync_invalidation_listener.h"
 #include "components/invalidation/public/invalidation_export.h"
 
 namespace syncer {
 
 // This class must live on the IO thread.
@@ skipping 63 matching lines @@
 
   // The invalidation listener.
   SyncInvalidationListener invalidation_listener_;
 
   DISALLOW_COPY_AND_ASSIGN(InvalidationNotifier);
 };
 
 }  // namespace syncer
 
 #endif  // COMPONENTS_INVALIDATION_IMPL_INVALIDATION_NOTIFIER_H_