Remove unused HostResolver::Observer.

net/base/host_resolver_impl.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_BASE_HOST_RESOLVER_IMPL_H_
 #define NET_BASE_HOST_RESOLVER_IMPL_H_
 #pragma once
 
 #include <vector>
 
@@ skipping 118 matching lines @@
   // HostResolver methods:
   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) 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 void ProbeIPv6Support() OVERRIDE;
   virtual HostCache* GetHostCache() OVERRIDE;
 
  private:
   // Allow tests to access our innards for testing purposes.
   friend class LookupAttemptHostResolverProc;
 
   // Allow tests to access our innards for testing purposes.
   FRIEND_TEST_ALL_PREFIXES(HostResolverImplTest, MultipleAttempts);
 
   class Job;
   class JobPool;
   class IPv6ProbeJob;
   class Request;
   typedef std::vector<Request*> RequestsList;
   typedef HostCache::Key Key;
   typedef std::map<Key, scoped_refptr<Job> > JobMap;
-  typedef std::vector<HostResolver::Observer*> ObserversList;
 
   // Helper used by |Resolve()| and |ResolveFromCache()|.  Performs IP
   // literal and cache lookup, returns OK if successful,
   // ERR_NAME_NOT_RESOLVED if either hostname is invalid or IP literal is
   // incompatible, ERR_DNS_CACHE_MISS if entry was not found in cache.
   int ResolveHelper(int request_id,
                     const Key& key,
                     const RequestInfo& info,
                     AddressList* addresses,
                     const BoundNetLog& request_net_log);
@@ skipping 150 matching lines @@
   uint32 retry_factor_;
 
   // The information to track pending requests for a JobPool, as well as
   // how many outstanding jobs the pool already has, and its constraints.
   JobPool* job_pools_[POOL_COUNT];
 
   // The job that OnJobComplete() is currently processing (needed in case
   // HostResolver gets deleted from within the callback).
   scoped_refptr<Job> cur_completing_job_;
 
-  // The observers to notify when a request starts/ends.
-  ObserversList observers_;
-
   // Monotonically increasing ID number to assign to the next request.
   // Observers are the only consumers of this ID number.
   int next_request_id_;

[eroman, 2011/11/14 20:01:39]

Can you delete this too? Or maybe it is still used by logging. In that case,
please update the comment to remove mention of "Observers".

[szym, 2011/11/14 23:50:17]

Currently HostResolverImpl does not use it, so I removed it.

However, I'm inclined to use an id as the RequestHandle (see
MockHostResolverBase). I'm not a fan of using opaque Request* (although it's
fast), because calling CancelRequest(req) after |req| has already been deleted
is scary. Perhaps it would help to document for the consumers that the
RequestHandle must not be used after the CompletionCallback is run.

[cbentzel, 2011/11/15 10:49:01]

You could always maintain a std::set<Request*> in the Host Resolver
implementations, and only cancel if it's present there. 

 
   // Monotonically increasing ID number to assign to the next job.
   // The only consumer of this ID is the requests tracing code.
   int next_job_id_;
 
   // The procedure to use for resolving host names. This will be NULL, except
   // in the case of unit-tests which inject custom host resolving behaviors.
   scoped_refptr<HostResolverProc> resolver_proc_;
 
   // Address family to use when the request doesn't specify one.
@@ skipping 11 matching lines @@
   HostResolverFlags additional_resolver_flags_;
 
   NetLog* net_log_;
 
   DISALLOW_COPY_AND_ASSIGN(HostResolverImpl);
 };
 
 }  // namespace net
 
 #endif  // NET_BASE_HOST_RESOLVER_IMPL_H_