[net/dns] Isolate DnsConfigWatcher from DnsConfigService.

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 eccacaa6538b57c7e826e1e51161f4199313ff5e..928a68825ea94f56e7702117cb0342b83a14a5e4 100644
--- a/net/base/network_change_notifier_win.cc
+++ b/net/base/network_change_notifier_win.cc
@@ -10,11 +10,15 @@
 #include "base/bind.h"
 #include "base/logging.h"
 #include "base/metrics/histogram.h"
+#include "base/threading/thread.h"
 #include "base/time.h"
 #include "net/base/winsock_init.h"
+#include "net/dns/dns_config_watcher.h"
 
 #pragma comment(lib, "iphlpapi.lib")
 
+namespace net {
+
 namespace {
 
 // Time between NotifyAddrChange retries, on failure.
@@ -22,14 +26,39 @@ const int kWatchForAddressChangeRetryIntervalMs = 500;
 
 }  // namespace
 
-namespace net {
+// Thread on which we can run DnsConfigWatcher, which requires AssertIOAllowed
+// to open registry keys and to handle FilePathWatcher updates.
+class NetworkChangeNotifierWin::DnsWatcherThread : public base::Thread {
+ public:
+  DnsWatcherThread() : base::Thread("NetworkChangeNotifier") {}
+
+  virtual ~DnsWatcherThread() {
+    Stop();
+  }
+
+  virtual void Init() OVERRIDE {
+    watcher_.Init();
+  }
+
+  virtual void CleanUp() OVERRIDE {
+    watcher_.CleanUp();
+  }
+
+ private:
+  internal::DnsConfigWatcher watcher_;
+
+  DISALLOW_COPY_AND_ASSIGN(DnsWatcherThread);
+};
 
 NetworkChangeNotifierWin::NetworkChangeNotifierWin()
     : is_watching_(false),
       sequential_failures_(0),
-      ALLOW_THIS_IN_INITIALIZER_LIST(weak_factory_(this)) {
+      ALLOW_THIS_IN_INITIALIZER_LIST(weak_factory_(this)),
+      dns_watcher_thread_(new DnsWatcherThread()) {
   memset(&addr_overlapped_, 0, sizeof addr_overlapped_);
   addr_overlapped_.hEvent = WSACreateEvent();
+  dns_watcher_thread_->StartWithOptions(
+      base::Thread::Options(MessageLoop::TYPE_IO, 0));
 }
 
 NetworkChangeNotifierWin::~NetworkChangeNotifierWin() {