cronet: Fix StaleHostResolver.AddressListDelta histogram.

components/cronet/stale_host_resolver.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/memory/ptr_util.h"
 #include "base/metrics/histogram_macros.h"
 #include "base/stl_util.h"
@@ skipping 277 matching lines @@
     network_request_.reset();
     result_callback_ = net::CompletionCallback();
     RecordCanceledRequest();
   }
 
   if (!returning_result_ && !have_handle() && !have_network_request())
     delete this;
 }
 
 int StaleHostResolver::RequestImpl::HandleResult(int rv,
                                                  net::AddressList* addresses) {

[xunjieli, 2016/11/01 21:14:16]

Can we change the argument from pointer to const ref? 
same for ReturnResult().

[Julia Tuttle, 2016/11/02 16:33:41]

Done.

   DCHECK(result_addresses_);
 
-  if (rv == net::OK) {
+  if (rv == net::OK)
     *result_addresses_ = *addresses;
-    addresses->clear();
-  }
   result_addresses_ = nullptr;
   return rv;
 }
 
 void StaleHostResolver::RequestImpl::ReturnResult(int rv,
                                                   net::AddressList* addresses) {
   DCHECK(result_callback_);
   returning_result_ = true;
   base::ResetAndReturn(&result_callback_).Run(HandleResult(rv, addresses));
   returning_result_ = false;
@@ skipping 76 matching lines @@
 
 net::HostCache* StaleHostResolver::GetHostCache() {
   return inner_resolver_->GetHostCache();
 }
 
 std::unique_ptr<base::Value> StaleHostResolver::GetDnsConfigAsValue() const {
   return inner_resolver_->GetDnsConfigAsValue();
 }
 
 }  // namespace net