chrome: Cleanup class/struct forward declarations

chrome/browser/local_discovery/service_discovery_client.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_LOCAL_DISCOVERY_SERVICE_DISCOVERY_CLIENT_H_
 #define CHROME_BROWSER_LOCAL_DISCOVERY_SERVICE_DISCOVERY_CLIENT_H_
 
 #include <memory>
 #include <string>
 #include <vector>
 
 #include "base/callback.h"
 #include "base/time/time.h"
 #include "net/base/address_family.h"
 #include "net/base/host_port_pair.h"
 #include "net/base/ip_address.h"
 
-namespace net {
-class MDnsClient;
-}
-
 namespace local_discovery {
 
 struct ServiceDescription {
  public:
   ServiceDescription();
   ServiceDescription(const ServiceDescription& other);
   ~ServiceDescription();
 
   // Convenience function to get useful parts of the service name. A service
   // name follows the format <instance_name>.<service_type>.
@@ skipping 97 matching lines @@
   // Create a resolver for local domain, both ipv4 or ipv6.
   virtual std::unique_ptr<LocalDomainResolver> CreateLocalDomainResolver(
       const std::string& domain,
       net::AddressFamily address_family,
       const LocalDomainResolver::IPAddressCallback& callback) = 0;
 };
 
 }  // namespace local_discovery
 
 #endif  // CHROME_BROWSER_LOCAL_DISCOVERY_SERVICE_DISCOVERY_CLIENT_H_