Prompt user before restarting System Preferences.

remoting/host/me2me_preference_pane.h

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #import <Cocoa/Cocoa.h>
 #import <PreferencePanes/PreferencePanes.h>
 #import <SecurityInterface/SFAuthorizationView.h>
 
 #include <string>
 
@@ skipping 47 matching lines @@
   // update...Status methods.
   BOOL is_service_running_;
   BOOL is_pane_unlocked_;
 
   // True if a new proposed config file has been loaded into memory.
   BOOL have_new_config_;
 
   // 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.  If true, this causes all
+  // controls to be greyed out, and also prevents any config file from being
+  // deleted, pending a restart of the preference pane.
+  BOOL is_pane_disabled_;
 }
 
 - (void)mainViewDidLoad;
 - (void)willSelect;
+- (void)didSelect;
 - (void)willUnselect;
 - (void)onDisable:(id)sender;
 - (void)applyConfiguration:(id)sender
                        pin:(NSString*)pin;
 - (void)onNewConfigFile:(NSNotification*)notification;
 - (void)refreshServiceStatus:(NSTimer*)timer;
 - (void)authorizationViewDidAuthorize:(SFAuthorizationView*)view;
 - (void)authorizationViewDidDeauthorize:(SFAuthorizationView*)view;
 - (void)updateServiceStatus;
 - (void)updateAuthorizationStatus;
 
 // Read any new config file if present.  If a config file is successfully read,
 // this deletes the file and keeps the config data loaded in memory.  If this
 // method is called a second time (when the file has been deleted), the current
 // config is remembered, so this method acts as a latch: it can change
 // |have_new_config_| from NO to YES, but never from YES to NO.
 //
 // This scheme means that this method can delete the file immediately (to avoid
 // 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.
 - (void)readNewConfig;
 
 // Update all UI controls according to any stored flags and loaded config.
 // This should be called after any sequence of operations that might change the
 // UI state.
 - (void)updateUI;
 
 // Alert the user to a generic error condition.
 - (void)showError;
 
 // Alert the user that the typed PIN is incorrect.
 - (void)showIncorrectPinMessage;
 
 // Save the new config to the system, and either start the service or inform
 // the currently-running service of the new config.
 - (void)applyNewServiceConfig;
 
 - (BOOL)runHelperAsRootWithCommand:(const char*)command
                          inputData:(const std::string&)input_data;
 - (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
+// |didSelect| 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 be kept until
+// System Preferences is restarted, or thrown away when the user cancels the
+// alert.  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