Remove unused HostResolver::Observer.

net/base/single_request_host_resolver_unittest.cc

 // 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.
 
 #include "net/base/single_request_host_resolver.h"
 
 #include "net/base/address_list.h"
 #include "net/base/mock_host_resolver.h"
 #include "net/base/net_errors.h"
 #include "net/base/net_log.h"
@@ skipping 39 matching lines @@
     NOTIMPLEMENTED();
     return ERR_UNEXPECTED;
   }
 
   virtual void CancelRequest(RequestHandle req) OVERRIDE {
     EXPECT_TRUE(has_outstanding_request());
     EXPECT_EQ(req, outstanding_request_);
     outstanding_request_ = NULL;
   }
 
-  virtual void AddObserver(Observer* observer) OVERRIDE {
-    FAIL();
-  }
-
-  virtual void RemoveObserver(Observer* observer) OVERRIDE {
-    FAIL();
-  }
-
  private:
   RequestHandle outstanding_request_;
 
   DISALLOW_COPY_AND_ASSIGN(HangingHostResolver);
 };
 
 // Test that a regular end-to-end lookup returns the expected result.
 TEST(SingleRequestHostResolverTest, NormalResolve) {
   // Create a host resolver dependency that returns address "199.188.1.166"
   // for resolutions of "watsup".
@@ skipping 44 matching lines @@
   SingleRequestHostResolver single_request_resolver(&resolver);
   single_request_resolver.Cancel();
 
   // To pass, HangingHostResolver should not have received a cancellation
   // request (since there is nothing to cancel). If it does, it will crash.
 }
 
 } // namespace
 
 }  // namespace net