Remove unused include in sequenced_worker_pool.h

blimp/client/core/session/assignment_source.h

 // 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.
 
 #ifndef BLIMP_CLIENT_CORE_SESSION_ASSIGNMENT_SOURCE_H_
 #define BLIMP_CLIENT_CORE_SESSION_ASSIGNMENT_SOURCE_H_
 
 #include <string>
 
 #include "base/callback.h"
+#include "base/memory/ref_counted.h"
 #include "base/memory/weak_ptr.h"
 #include "blimp/client/public/session/assignment.h"
 #include "net/url_request/url_fetcher_delegate.h"
 #include "url/gurl.h"
 
 namespace base {
 class FilePath;
 class SingleThreadTaskRunner;
 class Value;
 }
@@ skipping 54 matching lines @@
 
   base::WeakPtrFactory<AssignmentSource> weak_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(AssignmentSource);
 };
 
 }  // namespace client
 }  // namespace blimp
 
 #endif  // BLIMP_CLIENT_CORE_SESSION_ASSIGNMENT_SOURCE_H_