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

net/base/network_change_notifier_win.h

Index: net/base/network_change_notifier_win.h
diff --git a/net/base/network_change_notifier_win.h b/net/base/network_change_notifier_win.h
index aee5304ff6fe3d03506fa9827f99f55a1b16c14b..8058fbc308334859a07b7d90efd0226053e66f78 100644
--- a/net/base/network_change_notifier_win.h
+++ b/net/base/network_change_notifier_win.h
@@ -14,6 +14,8 @@
 #include "base/threading/non_thread_safe.h"
 #include "base/timer.h"
 #include "base/win/object_watcher.h"
+#include "base/win/registry.h"
+#include "net/base/file_path_watcher_callback.h"
 #include "net/base/net_export.h"
 #include "net/base/network_change_notifier.h"
 
@@ -41,6 +43,9 @@ class NET_EXPORT_PRIVATE NetworkChangeNotifierWin
  protected:
   virtual ~NetworkChangeNotifierWin();
 
+  // Begins listening for DNS changes.
+  void WatchForDNSChanges();
+
   // For unit tests only.
   bool is_watching() { return is_watching_; }
   void set_is_watching(bool is_watching) { is_watching_ = is_watching; }
@@ -49,9 +54,27 @@ class NET_EXPORT_PRIVATE NetworkChangeNotifierWin
  private:
   friend class NetworkChangeNotifierWinTest;
 
+  class RegistryWatcher : public base::win::ObjectWatcher::Delegate {
+   public:
+    explicit RegistryWatcher(NetworkChangeNotifierWin* notifier);
+    ~RegistryWatcher();
+
+    bool Watch(const wchar_t* key);
+    void Cancel();
+    virtual void OnObjectSignaled(HANDLE object) OVERRIDE;
+   private:
+    NetworkChangeNotifierWin* notifier_;
+    base::win::RegKey key_;
+    base::win::ObjectWatcher watcher_;
+
+    DISALLOW_COPY_AND_ASSIGN(RegistryWatcher);
+  };
+
   // NetworkChangeNotifier methods:
   virtual bool IsCurrentlyOffline() const OVERRIDE;
 
+  virtual bool IsCurrentlyWatchingDNS() const OVERRIDE;
+
   // ObjectWatcher::Delegate methods:
   // Must only be called on the thread |this| was created on.
   virtual void OnObjectSignaled(HANDLE object) OVERRIDE;
@@ -70,6 +93,13 @@ class NET_EXPORT_PRIVATE NetworkChangeNotifierWin
   // created on.
   virtual bool WatchForAddressChangeInternal();
 
+  // Called by RegistryWatcher. |watch_successful| is true iff the watch
+  // continues successfully.
+  void OnRegistryChanged(bool watch_successful);
+
+  // Called by FilePathWatcherCallback.
+  void OnDNSFileChanged(bool watch_successful);
+
   // All member variables may only be accessed on the thread |this| was created
   // on.
 
@@ -86,6 +116,14 @@ class NET_EXPORT_PRIVATE NetworkChangeNotifierWin
   // Number of times WatchForAddressChange has failed in a row.
   int sequential_failures_;
 
+  bool watching_dns_;
+  // One watcher per key of interest.
+  RegistryWatcher dns_policy_watcher_;
+  RegistryWatcher dns_dnscache_watcher_;
+  RegistryWatcher dns_tcpip_watcher_;
+
+  FilePathWatcherCallback hosts_watcher_;
+
   // Used for calling WatchForAddressChange again on failure.
   base::WeakPtrFactory<NetworkChangeNotifierWin> weak_factory_;