[net] Add DNS-related signals and NetLog to NetworkChangeNotifier.

net/base/network_change_notifier_win.cc

Index: net/base/network_change_notifier_win.cc
diff --git a/net/base/network_change_notifier_win.cc b/net/base/network_change_notifier_win.cc
index e1307447bc326ce2d2a47152175ab400f6cd7ee2..5c04820768366b3b737e405ab731d9000ac61ccf 100644
--- a/net/base/network_change_notifier_win.cc
+++ b/net/base/network_change_notifier_win.cc
@@ -27,9 +27,14 @@ namespace net {
 NetworkChangeNotifierWin::NetworkChangeNotifierWin()
     : is_watching_(false),
       sequential_failures_(0),
+      dns_policy_watcher_(this),
+      dns_dnscache_watcher_(this),
+      dns_tcpip_watcher_(this),
       ALLOW_THIS_IN_INITIALIZER_LIST(weak_factory_(this)) {
   memset(&addr_overlapped_, 0, sizeof addr_overlapped_);
   addr_overlapped_.hEvent = WSACreateEvent();
+
+  WatchForDNSChanges();
 }
 
 NetworkChangeNotifierWin::~NetworkChangeNotifierWin() {
@@ -157,6 +162,11 @@ bool NetworkChangeNotifierWin::IsCurrentlyOffline() const {
   return !found_connection;
 }
 
+
+bool NetworkChangeNotifierWin::IsCurrentlyWatchingDNS() const {
+  return watching_dns_;
+}
+
 void NetworkChangeNotifierWin::OnObjectSignaled(HANDLE object) {
   DCHECK(CalledOnValidThread());
   DCHECK(is_watching_);
@@ -234,8 +244,90 @@ bool NetworkChangeNotifierWin::WatchForAddressChangeInternal() {
   return true;
 }
 
+void NetworkChangeNotifierWin::WatchForDNSChanges() {
+  TCHAR buffer[MAX_PATH];
+  UINT rc = GetSystemDirectory(buffer, MAX_PATH);
+  DCHECK(0 < rc && rc < MAX_PATH);
+  FilePath hosts_path = FilePath(buffer).
+      Append(FILE_PATH_LITERAL("drivers\\etc\\hosts"));
+
+  // DNS suffix search list and devolution can be configured via group
+  // policy which sets this registry key. If the key is missing, the policy
+  // does not apply, and the DNS client uses Tcpip and Dnscache settings.
+  // If a policy is installed, DnsConfigService will need to be restarted.
+  // http://crbug.com/99509
+  dns_policy_watcher_.Watch(
+      L"SOFTWARE\\Policies\\Microsoft\\Windows NT\\DNSClient");
+  dns_dnscache_watcher_.Watch(
+      L"SYSTEM\\CurrentControlSet\\Services\\Dnscache\\Parameters");
+  if (!dns_tcpip_watcher_.Watch(
+          L"SYSTEM\\CurrentControlSet\\Services\\Tcpip\\Parameters") &&
+      hosts_watcher_.Watch(
+          hosts_path,
+          base::Bind(&NetworkChangeNotifierWin::OnDNSFileChanged,
+                     base::Unretained(this)))) {
+    watching_dns_ = true;
+  } else {
+    watching_dns_ = false;
+    LOG(ERROR) << "Failed to start DNS watch";
+  }
+}
+
 void NetworkChangeNotifierWin::NotifyParentOfOnlineStateChange() {
   NotifyObserversOfOnlineStateChange();
 }
 
+void NetworkChangeNotifierWin::OnRegistryChanged(bool watch_successful) {
+  if (!watch_successful) {
+    LOG(ERROR) << "DNS settings watch failed.";
+    watching_dns_ = false;
+  }
+  // TODO(szym): depending on the key, we should indicate CHANGE_DNS_LOCALHOST.
+  NotifyObserversOfDNSChange(CHANGE_DNS_SETTINGS);
+}
+
+void NetworkChangeNotifierWin::OnDNSFileChanged(bool watch_successful) {
+  if (!watch_successful) {
+    LOG(ERROR) << "DNS hosts watch failed.";
+    watching_dns_ = false;
+  }
+  NotifyObserversOfDNSChange(CHANGE_DNS_HOSTS);
+}
+
+NetworkChangeNotifierWin::RegistryWatcher::RegistryWatcher(
+    NetworkChangeNotifierWin* notifier) : notifier_(notifier) {
+}
+
+NetworkChangeNotifierWin::RegistryWatcher::~RegistryWatcher() {
+  Cancel();
+}
+
+bool NetworkChangeNotifierWin::RegistryWatcher::Watch(const wchar_t* key) {
+  if (key_.Valid())
+    Cancel();
+  if (key_.Open(HKEY_LOCAL_MACHINE, key,
+                KEY_NOTIFY | KEY_QUERY_VALUE) != ERROR_SUCCESS)
+    return false;
+  if (key_.StartWatching() != ERROR_SUCCESS)
+    return false;
+  if (!watcher_.StartWatching(key_.watch_event(), this))
+    return false;
+  return true;
+}
+
+void NetworkChangeNotifierWin::RegistryWatcher::Cancel() {
+  key_.StopWatching();
+  watcher_.StopWatching();
+  key_.Close();
+}
+
+void NetworkChangeNotifierWin::RegistryWatcher::OnObjectSignaled(
+    HANDLE object) {
+  bool success = key_.StartWatching() &&
+                 watcher_.StartWatching(key_.watch_event(), this);
+  if (!success)
+    Cancel();
+  notifier_->OnRegistryChanged(success);
+}
+
 }  // namespace net