chromeos: Cleanup class/struct fwd declarations

chromeos/network/onc/onc_certificate_importer_impl.h

 // Copyright 2013 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.
 
 #ifndef CHROMEOS_NETWORK_ONC_ONC_CERTIFICATE_IMPORTER_IMPL_H_
 #define CHROMEOS_NETWORK_ONC_ONC_CERTIFICATE_IMPORTER_IMPL_H_
 
 #include <map>
 #include <memory>
 #include <string>
 #include <vector>
 
 #include "base/macros.h"
 #include "base/memory/ref_counted.h"
 #include "base/memory/weak_ptr.h"
 #include "chromeos/chromeos_export.h"
 #include "chromeos/network/onc/onc_certificate_importer.h"
 #include "components/onc/onc_constants.h"
 
 namespace base {
 class DictionaryValue;
 class ListValue;
 class SequencedTaskRunner;
-class SingleThreadTaskRunner;
 }
 
 namespace net {
 class NSSCertDatabase;
 class X509Certificate;
 typedef std::vector<scoped_refptr<X509Certificate> > CertificateList;
 }
 
 namespace chromeos {
 namespace onc {
@@ skipping 61 matching lines @@
 
   base::WeakPtrFactory<CertificateImporterImpl> weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(CertificateImporterImpl);
 };
 
 }  // namespace onc
 }  // namespace chromeos
 
 #endif  // CHROMEOS_NETWORK_ONC_ONC_CERTIFICATE_IMPORTER_IMPL_H_