Remove unused HostResolver::Observer.

net/dns/async_host_resolver.h

 // Copyright (c) 2011 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 NET_DNS_ASYNC_HOST_RESOLVER_H_
 #define NET_DNS_ASYNC_HOST_RESOLVER_H_
 #pragma once
 
 #include <list>
 #include <map>
 
-#include "base/observer_list.h"
 #include "base/threading/non_thread_safe.h"
 #include "net/base/address_family.h"
 #include "net/base/host_cache.h"
 #include "net/base/host_resolver.h"
 #include "net/base/ip_endpoint.h"
 #include "net/base/net_log.h"
 #include "net/base/rand_callback.h"
 #include "net/dns/dns_transaction.h"
 
 namespace net {
@@ skipping 17 matching lines @@
   // HostResolver interface
   virtual int Resolve(const RequestInfo& info,
                       AddressList* addresses,
                       OldCompletionCallback* callback,
                       RequestHandle* out_req,
                       const BoundNetLog& source_net_log) OVERRIDE;
   virtual int ResolveFromCache(const RequestInfo& info,
                                AddressList* addresses,
                                const BoundNetLog& source_net_log) OVERRIDE;
   virtual void CancelRequest(RequestHandle req_handle) OVERRIDE;
-  virtual void AddObserver(HostResolver::Observer* observer) OVERRIDE;
-  virtual void RemoveObserver(HostResolver::Observer* observer) OVERRIDE;
   virtual void SetDefaultAddressFamily(AddressFamily address_family) OVERRIDE;
   virtual AddressFamily GetDefaultAddressFamily() const OVERRIDE;
   virtual HostCache* GetHostCache() OVERRIDE;
 
   // DnsTransaction::Delegate interface
   virtual void OnTransactionComplete(
       int result,
       const DnsTransaction* transaction,
       const IPAddressList& ip_addresses) OVERRIDE;
 
@@ skipping 76 matching lines @@
   // Callback to be passed to DnsTransaction for generating DNS query ids.
   RandIntCallback rand_int_cb_;
 
   // Cache of host resolution results.
   scoped_ptr<HostCache> cache_;
 
   // Also passed to DnsTransaction; it's a dependency injection to aid
   // testing, outside of unit tests, its value is always NULL.
   ClientSocketFactory* factory_;
 
-  // The observers to notify when a request starts/ends.
-  ObserverList<HostResolver::Observer> observers_;
-
-  // Monotonically increasing ID number to assign to the next request.
+    // Monotonically increasing ID number to assign to the next request.
   // Observers are the only consumers of this ID number.
   int next_request_id_;
 
   NetLog* net_log_;
 
   DISALLOW_COPY_AND_ASSIGN(AsyncHostResolver);
 };
 
 }  // namespace net
 
 #endif  // NET_DNS_ASYNC_HOST_RESOLVER_H_