Detect if user closes the pref-pane without disabling Chromoting

remoting/host/me2me_preference_pane.mm

Index: remoting/host/me2me_preference_pane.mm
diff --git a/remoting/host/me2me_preference_pane.mm b/remoting/host/me2me_preference_pane.mm
index ac33b13eb329ad3a275c923e5725bf0d183b85ce..5d8cec82c44c75928aab6beae1307590948e8b59 100644
--- a/remoting/host/me2me_preference_pane.mm
+++ b/remoting/host/me2me_preference_pane.mm
@@ -35,6 +35,18 @@ namespace {
 #define kUpdateSucceededNotificationName kServiceName ".update_succeeded"
 #define kUpdateFailedNotificationName kServiceName ".update_failed"
 
+// This notification (or the UpdateFailed notification) is sent whenever the
+// pref-pane is deselected.  This is analogous to the user canceling the
+// confirm-PIN dialog (or UAC prompt) on Windows.
+// If the plugin is expecting an action to occur (such as the user disabling
+// the Host service), it should treat this as a signal to stop waiting, and
+// assume the action has been canceled by the user.
+// Otherwise, the plugin should ignore this notification.  The pref-pane does
+// not know whether it was launched by the plugin or by the user (in the case
+// of disabling remote connections), so it has to send this notification
+// regardless.
+#define kUserCanceledNotificationName kServiceName ".user_canceled"

[Jamie, 2012/06/15 22:34:56]

Can we call this update_canceled for consistency with the other two?

+
 #define kConfigDir "/Library/PrivilegedHelperTools/"
 
 // This helper script is executed as root.  It is passed a command-line option
@@ -329,6 +341,8 @@ std::string JsonHostConfig::GetSerializedData() const {
   service_status_timer_ = nil;
   if (have_new_config_)
     [self notifyPlugin:kUpdateFailedNotificationName];
+  else
+    [self notifyPlugin:kUserCanceledNotificationName];

[Jamie, 2012/06/15 22:34:56]

This feels inconsistent. Why send a failed notification for the "start/change
PIN" pane, but a canceled notification for the "stop" pane?

 }
 
 - (void)applyConfiguration:(id)sender
@@ -753,11 +767,12 @@ std::string JsonHostConfig::GetSerializedData() const {
       NSLog(@"Failed to get path of configuration data.");
       return;
     }
-    if (access(file.c_str(), F_OK) != 0)
-      return;
-
-    remove(file.c_str());
-    [self notifyPlugin:kUpdateFailedNotificationName];
+    if (access(file.c_str(), F_OK) != 0) {
+      [self notifyPlugin:kUserCanceledNotificationName];

[Jamie, 2012/06/15 22:34:56]

Under what circumstances can this happen? Would it make sense to send an error
notification instead?

+    } else {
+      remove(file.c_str());
+      [self notifyPlugin:kUpdateFailedNotificationName];
+    }
   }
 }