Make ~StaleHostResolverTest override.

components/cronet/stale_host_resolver_unittest.cc

 // Copyright 2016 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 "components/cronet/stale_host_resolver.h"
 
 #include "base/callback_helpers.h"
 #include "base/logging.h"
 #include "base/memory/ptr_util.h"
 #include "base/memory/ref_counted.h"
@@ skipping 61 matching lines @@
 };
 
 class StaleHostResolverTest : public testing::Test {
  protected:
   StaleHostResolverTest()
       : mock_proc_(new MockHostResolverProc()),
         resolver_(nullptr),
         resolve_pending_(false),
         resolve_complete_(false) {}
 
-  ~StaleHostResolverTest() {}
+  ~StaleHostResolverTest() override {}
 
   void SetStaleDelay(int stale_delay_sec) {
     DCHECK(!resolver_);
 
     options_.delay = base::TimeDelta::FromSeconds(stale_delay_sec);
   }
 
   void SetStaleUsability(int max_expired_time_sec,
                          int max_stale_uses,
                          bool allow_other_network) {
@@ skipping 395 matching lines @@
 
   EXPECT_TRUE(resolve_complete());
   EXPECT_EQ(net::OK, resolve_error());
   EXPECT_EQ(1u, resolve_addresses().size());
   EXPECT_EQ(kCacheAddress, resolve_addresses()[0].ToStringWithoutPort());
 }
 
 }  // namespace
 
 }  // namespace cronet