[net] Move DnsConfigService to NetworkChangeNotifier.

net/dns/dns_config_service.cc

 // Copyright (c) 2012 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/dns/dns_config_service.h"
 
 #include "base/logging.h"
 #include "base/metrics/histogram.h"
 #include "base/values.h"
 #include "net/base/ip_endpoint.h"
@@ skipping 57 matching lines @@
   dict->SetInteger("attempts", attempts);
   dict->SetBoolean("rotate", rotate);
   dict->SetBoolean("edns0", edns0);
   dict->SetInteger("num_hosts", hosts.size());
 
   return dict;
 }
 
 
 DnsConfigService::DnsConfigService()
-    : have_config_(false),
+    : watch_failed_(false),
+      have_config_(false),
       have_hosts_(false),
       need_update_(false),
       last_sent_empty_(true) {}
 
 DnsConfigService::~DnsConfigService() {
-  // Must always clean up.
-  NetworkChangeNotifier::RemoveDNSObserver(this);
 }
 
-void DnsConfigService::Read(const CallbackType& callback) {
+void DnsConfigService::ReadConfig(const CallbackType& callback) {
   DCHECK(CalledOnValidThread());
   DCHECK(!callback.is_null());
   DCHECK(callback_.is_null());
   callback_ = callback;
-  OnDNSChanged(NetworkChangeNotifier::CHANGE_DNS_WATCH_STARTED);
+  ReadNow();
 }
 
-void DnsConfigService::Watch(const CallbackType& callback) {
+void DnsConfigService::WatchConfig(const CallbackType& callback) {
   DCHECK(CalledOnValidThread());
   DCHECK(!callback.is_null());
   DCHECK(callback_.is_null());
-  NetworkChangeNotifier::AddDNSObserver(this);
   callback_ = callback;
-  if (NetworkChangeNotifier::IsWatchingDNS())
-    OnDNSChanged(NetworkChangeNotifier::CHANGE_DNS_WATCH_STARTED);
-  // else: Wait until signal before reading.
+  watch_failed_ = !StartWatching();
+  ReadNow();
 }
 
 void DnsConfigService::InvalidateConfig() {
   DCHECK(CalledOnValidThread());
   base::TimeTicks now = base::TimeTicks::Now();
   if (!last_invalidate_config_time_.is_null()) {
     UMA_HISTOGRAM_LONG_TIMES("AsyncDNS.ConfigNotifyInterval",
                              now - last_invalidate_config_time_);
   }
   last_invalidate_config_time_ = now;
@@ skipping 27 matching lines @@
     need_update_ = true;
     changed = true;
   }
   if (!changed && !last_sent_empty_time_.is_null()) {
     UMA_HISTOGRAM_LONG_TIMES("AsyncDNS.UnchangedConfigInterval",
                              base::TimeTicks::Now() - last_sent_empty_time_);
   }
   UMA_HISTOGRAM_BOOLEAN("AsyncDNS.ConfigChange", changed);
 
   have_config_ = true;
-  if (have_hosts_)
+  if (have_hosts_ || watch_failed_)
     OnCompleteConfig();
 }
 
 void DnsConfigService::OnHostsRead(const DnsHosts& hosts) {
   DCHECK(CalledOnValidThread());
 
   bool changed = false;
   if (hosts != dns_config_.hosts) {
     dns_config_.hosts = hosts;
     need_update_ = true;
     changed = true;
   }
   if (!changed && !last_sent_empty_time_.is_null()) {
     UMA_HISTOGRAM_LONG_TIMES("AsyncDNS.UnchangedHostsInterval",
                              base::TimeTicks::Now() - last_sent_empty_time_);
   }
   UMA_HISTOGRAM_BOOLEAN("AsyncDNS.HostsChange", changed);
 
   have_hosts_ = true;
-  if (have_config_)
+  if (have_config_ || watch_failed_)
     OnCompleteConfig();
 }
 
 void DnsConfigService::StartTimer() {
   DCHECK(CalledOnValidThread());
   if (last_sent_empty_) {
     DCHECK(!timer_.IsRunning());
     return;  // No need to withdraw again.
   }
   timer_.Stop();
@@ skipping 26 matching lines @@
   last_sent_empty_time_ = base::TimeTicks::Now();
   callback_.Run(DnsConfig());
 }
 
 void DnsConfigService::OnCompleteConfig() {
   timer_.Stop();
   if (!need_update_)
     return;
   need_update_ = false;
   last_sent_empty_ = false;
-  callback_.Run(dns_config_);
+  if (watch_failed_) {
+    // If a watch failed, the config may not be accurate, so report empty.
+    callback_.Run(DnsConfig());
+  } else {
+    callback_.Run(dns_config_);
+  }
 }
 
 }  // namespace net