Virtual destructors should have virtual keyword.

net/base/mock_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_BASE_MOCK_HOST_RESOLVER_H_
 #define NET_BASE_MOCK_HOST_RESOLVER_H_
 #pragma once
 
 #include <list>
 
@@ skipping 77 matching lines @@
 };
 
 // Same as MockHostResolver, except internally it uses a host-cache.
 //
 // Note that tests are advised to use MockHostResolver instead, since it is
 // more predictable. (MockHostResolver also can be put into synchronous
 // operation mode in case that is what you needed from the caching version).
 class MockCachingHostResolver : public MockHostResolverBase {
  public:
   MockCachingHostResolver() : MockHostResolverBase(true /*use_caching*/) {}
-  ~MockCachingHostResolver() {}
+  virtual ~MockCachingHostResolver() {}
 };
 
 // RuleBasedHostResolverProc applies a set of rules to map a host string to
 // a replacement host string. It then uses the system host resolver to return
 // a socket address. Generally the replacement should be an IPv4 literal so
 // there is no network dependency.
 class NET_TEST RuleBasedHostResolverProc : public HostResolverProc {
  public:
   explicit RuleBasedHostResolverProc(HostResolverProc* previous);
 
@@ skipping 31 matching lines @@
   virtual int Resolve(const std::string& host,
                       AddressFamily address_family,
                       HostResolverFlags host_resolver_flags,
                       AddressList* addrlist,
                       int* os_error);
 
  private:
   struct Rule;
   typedef std::list<Rule> RuleList;
 
-  ~RuleBasedHostResolverProc();
+  virtual ~RuleBasedHostResolverProc();
 
   RuleList rules_;
 };
 
 // Using WaitingHostResolverProc you can simulate very long lookups.
 class NET_TEST WaitingHostResolverProc : public HostResolverProc {
  public:
   explicit WaitingHostResolverProc(HostResolverProc* previous);
 
   void Signal();
@@ skipping 30 matching lines @@
   void Init(HostResolverProc* proc);
 
  private:
   scoped_refptr<HostResolverProc> current_proc_;
   scoped_refptr<HostResolverProc> previous_proc_;
 };
 
 }  // namespace net
 
 #endif  // NET_BASE_MOCK_HOST_RESOLVER_H_