chrome: Cleanup class/struct forward declarations

chrome/browser/extensions/api/mdns/dns_sd_registry.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 CHROME_BROWSER_EXTENSIONS_API_MDNS_DNS_SD_REGISTRY_H_
 #define CHROME_BROWSER_EXTENSIONS_API_MDNS_DNS_SD_REGISTRY_H_
 
 #include <map>
 #include <memory>
 #include <string>
 #include <utility>
 #include <vector>
 
 #include "base/macros.h"
 #include "base/observer_list.h"
 #include "chrome/browser/extensions/api/mdns/dns_sd_delegate.h"
 
 namespace local_discovery {
 class ServiceDiscoverySharedClient;
-class ServiceDiscoveryClient;
 }
 
 namespace extensions {
 
 class DnsSdDeviceLister;
 class ServiceTypeData;
 
 // Registry class for keeping track of discovered network services over DNS-SD.
 class DnsSdRegistry : public DnsSdDelegate {
  public:
@@ skipping 84 matching lines @@
   scoped_refptr<local_discovery::ServiceDiscoverySharedClient>
       service_discovery_client_;
   base::ObserverList<DnsSdObserver> observers_;
 
   DISALLOW_COPY_AND_ASSIGN(DnsSdRegistry);
 };
 
 }  // namespace extensions
 
 #endif  // CHROME_BROWSER_EXTENSIONS_API_MDNS_DNS_SD_REGISTRY_H_