Prompt user before restarting System Preferences.

remoting/host/me2me_preference_pane.h

Index: remoting/host/me2me_preference_pane.h
diff --git a/remoting/host/me2me_preference_pane.h b/remoting/host/me2me_preference_pane.h
index 8ddf0b2424214530db4496b5b64901ffab80a61b..668d8764bbab53c1eb87595a294c6d9bed9063cb 100644
--- a/remoting/host/me2me_preference_pane.h
+++ b/remoting/host/me2me_preference_pane.h
@@ -65,10 +65,15 @@ class JsonHostConfig {
   // True if launchd has been instructed to stop the service and we are waiting
   // for the operation to complete.
   BOOL awaiting_service_stop_;
+
+  // True if a version-mismatch has been detected and the whole pane has to be
+  // disabled.
+  BOOL is_pane_disabled_;

[Jamie, 2012/06/06 16:26:49]

Now that I understand better what's going on here, I think a better name for
this would be something like |confirm_restart_pending_or_canceled_|. The fact
that the pane is disabled is just one consequence of being in this state. As
your comment below describes, there are other consequences.

[Lambros, 2012/06/07 00:25:28]

Done.

 }
 
 - (void)mainViewDidLoad;
 - (void)willSelect;
+- (void)didSelect;
 - (void)willUnselect;
 - (void)onDisable:(id)sender;
 - (void)applyConfiguration:(id)sender
@@ -90,6 +95,10 @@ class JsonHostConfig {
 // leaving a stale file around in case of a crash), but this method can safely
 // be called multiple times without forgetting the loaded config.  To explicitly
 // forget the current config, set |have_new_config_| to NO.
+//
+// This method first checks that the pane has not been disabled due to a
+// pending restart.  If |is_pane_disabled_| is YES, this method does nothing,
+// leaving the config file untouched.

[Jamie, 2012/06/01 18:53:26]

Is this second sentence still correct? Since cancelling the "please restart"
prompt now sends a "failed" message back to the web-app, I don't think it's
necessary to retain the config file that we would have read had there been no
version mismatch.

[Lambros, 2012/06/05 17:57:39]

Yes.  Cancelling the "please restart" prompt now sends a "failed" message back
to the web-app AND deletes the config file.

The config file must be kept if |is_pane_disabled_| is YES, because the user
might not have chosen OK yet on the warning that has popped up or is about to be
popped up.

[Jamie, 2012/06/06 16:26:49]

Perhaps it would be better not to call this method in that case, then you
wouldn't need this comment. Right now this function doesn't quite do what its
name suggests, which is always a potential source of confusion.

[Lambros, 2012/06/07 00:25:28]

Done.

 - (void)readNewConfig;
 
 // Update all UI controls according to any stored flags and loaded config.
@@ -112,8 +121,26 @@ class JsonHostConfig {
 - (BOOL)sendJobControlMessage:(const char*)launch_key;
 
 // Compare the version of the running pref-pane against the installed version.
-// If the versions are mismatched, return YES and restart the System
-// Preferences application, so the correct version of this pref-pane is loaded.
-- (BOOL)restartPanelIfDifferentVersionInstalled;
+// If the versions are mismatched and the pref-pane is visible, disable the
+// pane to prevent interaction, and prompt the user to restart System
+// Preferences.
+//
+// This should be called on notification of a new config, and also in
+// |didShow| when the pane becomes visible.  The pane needs to be visible so
+// that the alert appears as a sheet over the pane (instead of a detached
+// window), which gives the user an appropriate context for the alert.
+//
+// In the case of a version-mismatch, the new config file should not be deleted
+// until System Preferences is restarted.  This method sets the
+// |is_pane_disabled_| flag on version-mismatch, which is checked by
+// |readNewConfig|.
+- (void)checkInstalledVersion;
+
+- (void)mismatchAlertDidEnd:(NSAlert*)alert
+                 returnCode:(NSInteger)returnCode
+                contextInfo:(void*)contextInfo;
+
+// Called when the user chooses OK when prompted to restart System Preferences.
+- (void)restartSystemPreferences;
 
 @end