[net/dns] Isolate DnsConfigWatcher from DnsConfigService.

net/dns/dns_config_service_posix.cc

Index: net/dns/dns_config_service_posix.cc
diff --git a/net/dns/dns_config_service_posix.cc b/net/dns/dns_config_service_posix.cc
index a53739e1ba873b3a29c9d04c42b64821dca7772b..11a48a534386e9dd7c623615b92ee4ea6aa49858 100644
--- a/net/dns/dns_config_service_posix.cc
+++ b/net/dns/dns_config_service_posix.cc
@@ -16,18 +16,14 @@
 #include "net/dns/file_path_watcher_wrapper.h"
 #include "net/dns/serial_worker.h"
 
-#if defined(OS_MACOSX)
-#include "net/dns/notify_watcher_mac.h"
-#endif
+namespace net {
+
+namespace {
 
 #ifndef _PATH_RESCONF  // Normally defined in <resolv.h>
 #define _PATH_RESCONF "/etc/resolv.conf"
 #endif
 
-namespace net {
-
-namespace {
-
 const FilePath::CharType* kFilePathHosts = FILE_PATH_LITERAL("/etc/hosts");
 
 // A SerialWorker that uses libresolv to initialize res_state and converts
@@ -85,32 +81,7 @@ class ConfigReader : public SerialWorker {
 
 namespace internal {
 
-#if defined(OS_MACOSX)
-// From 10.7.3 configd-395.10/dnsinfo/dnsinfo.h
-static const char* kDnsNotifyKey =
-    "com.apple.system.SystemConfiguration.dns_configuration";
-
-class DnsConfigServicePosix::ConfigWatcher : public NotifyWatcherMac {
- public:
-  bool Watch(const base::Callback<void(bool succeeded)>& callback) {
-    return NotifyWatcherMac::Watch(kDnsNotifyKey, callback);
-  }
-};
-#else
-static const FilePath::CharType* kFilePathConfig =
-    FILE_PATH_LITERAL(_PATH_RESCONF);
-
-class DnsConfigServicePosix::ConfigWatcher : public FilePathWatcherWrapper {
- public:
-  bool Watch(const base::Callback<void(bool succeeded)>& callback) {
-    return FilePathWatcherWrapper::Watch(FilePath(kFilePathConfig), callback);
-  }
-};
-#endif
-
-DnsConfigServicePosix::DnsConfigServicePosix()
-    : config_watcher_(new ConfigWatcher()),
-      hosts_watcher_(new FilePathWatcherWrapper()) {
+DnsConfigServicePosix::DnsConfigServicePosix() {
   config_reader_ = new ConfigReader(
       base::Bind(&DnsConfigServicePosix::OnConfigRead,
                  base::Unretained(this)));
@@ -125,46 +96,25 @@ DnsConfigServicePosix::~DnsConfigServicePosix() {
   hosts_reader_->Cancel();
 }
 
-void DnsConfigServicePosix::Watch(const CallbackType& callback) {
-  DCHECK(CalledOnValidThread());
-  DCHECK(!callback.is_null());
-  set_callback(callback);
-
-  // Even if watchers fail, we keep the other one as it provides useful signals.
-  if (config_watcher_->Watch(
-          base::Bind(&DnsConfigServicePosix::OnConfigChanged,
-                     base::Unretained(this)))) {
-    OnConfigChanged(true);
-  } else {
-    OnConfigChanged(false);
-  }
-
-  if (hosts_watcher_->Watch(
-          FilePath(kFilePathHosts),
-          base::Bind(&DnsConfigServicePosix::OnHostsChanged,
-                     base::Unretained(this)))) {
-    OnHostsChanged(true);
-  } else {
-    OnHostsChanged(false);
+void DnsConfigServicePosix::OnDNSChanged(unsigned detail) {

[mmenke, 2012/05/16 16:18:03]

This function is identical on Windows and posix.  Think this CL is big enough as
is, but in a future CL, may be nice to have this function in the parent class. 
Then you can also mock out the readers and run tests by mimicking OnDNSChanged
events, and return configs via Gmock.

+  if (detail & NetworkChangeNotifier::CHANGE_DNS_WATCH_FAILED) {
+    InvalidateConfig();
+    InvalidateHosts();
+    // We don't trust a config that we cannot watch in the future.
+    config_reader_->Cancel();
+    hosts_reader_->Cancel();
+    return;
   }
-}
-
-void DnsConfigServicePosix::OnConfigChanged(bool watch_succeeded) {
-  InvalidateConfig();
-  // We don't trust a config that we cannot watch in the future.
-  // TODO(szym): re-start watcher if that makes sense. http://crbug.com/116139
-  if (watch_succeeded)
+  if (detail & NetworkChangeNotifier::CHANGE_DNS_WATCH_STARTED)
+    detail = ~0;  // Assume everything changed.
+  if (detail & NetworkChangeNotifier::CHANGE_DNS_SETTINGS) {
+    InvalidateConfig();
     config_reader_->WorkNow();
-  else
-    LOG(ERROR) << "Failed to watch DNS config";
-}
-
-void DnsConfigServicePosix::OnHostsChanged(bool watch_succeeded) {
-  InvalidateHosts();
-  if (watch_succeeded)
+  }
+  if (detail & NetworkChangeNotifier::CHANGE_DNS_HOSTS) {
+    InvalidateHosts();
     hosts_reader_->WorkNow();
-  else
-    LOG(ERROR) << "Failed to watch DNS hosts";
+  }
 }
 
 #if !defined(OS_ANDROID)