Remove unused HostResolver::Observer.

net/base/host_resolver_impl.h

Index: net/base/host_resolver_impl.h
diff --git a/net/base/host_resolver_impl.h b/net/base/host_resolver_impl.h
index dd8cb4d47167ae40475f6453b4f7d0c58c216b58..e699ad7cc0e5e1fd8e289d84a47384edaaa93f10 100644
--- a/net/base/host_resolver_impl.h
+++ b/net/base/host_resolver_impl.h
@@ -136,8 +136,6 @@ class NET_EXPORT HostResolverImpl
                                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;
@@ -157,14 +155,12 @@ class NET_EXPORT HostResolverImpl
   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,
+  int ResolveHelper(const Key& key,
                     const RequestInfo& info,
                     AddressList* addresses,
                     const BoundNetLog& request_net_log);
@@ -215,13 +211,11 @@ class NET_EXPORT HostResolverImpl
   // Called when a request has just been started.
   void OnStartRequest(const BoundNetLog& source_net_log,
                       const BoundNetLog& request_net_log,
-                      int request_id,
                       const RequestInfo& info);
 
   // Called when a request has just completed (before its callback is run).
   void OnFinishRequest(const BoundNetLog& source_net_log,
                        const BoundNetLog& request_net_log,
-                       int request_id,
                        const RequestInfo& info,
                        int net_error,
                        int os_error);
@@ -229,7 +223,6 @@ class NET_EXPORT HostResolverImpl
   // Called when a request has been cancelled.
   void OnCancelRequest(const BoundNetLog& source_net_log,
                        const BoundNetLog& request_net_log,
-                       int request_id,
                        const RequestInfo& info);
 
   // Notify IPv6ProbeJob not to call back, and discard reference to the job.
@@ -328,13 +321,6 @@ class NET_EXPORT HostResolverImpl
   // 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_;
-
   // 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_;