Add support for meta_restart() and MetaDisplay::restart

Support was added to Mutter to allow it to trigger a restart
to allow for restarts when switching in or out of stereo mode.

Hook up to the new signals on MetaDisplay to show the restart
message and reexec. Meta.is_restart() is used to suppress
the startup animation.

This also allows us to do 'Alt-F2 r' restarts more cleanly
without a visual flash and animation.

https://bugzilla.gnome.org/show_bug.cgi?id=733026

js/ui/main.js

@@ -18,6 +18,7 @@ const ExtensionSystem = imports.ui.extensionSystem;
 const ExtensionDownloader = imports.ui.extensionDownloader;
 const Keyboard = imports.ui.keyboard;
 const MessageTray = imports.ui.messageTray;
+const ModalDialog = imports.ui.modalDialog;
 const OsdWindow = imports.ui.osdWindow;
 const Overview = imports.ui.overview;
 const Panel = imports.ui.panel;
@@ -167,6 +168,16 @@ function _initializeUI() {
             overview.toggle();
     }));
 
+    global.display.connect('show-restart-message', function(display, message) {
+        showRestartMessage(message);
+        return true;
+    });
+
+    global.display.connect('restart', function() {
+        global.reexec_self();
+        return true;
+    });
+
     // Provide the bus object for gnome-session to
     // initiate logouts.
     EndSessionDialog.init();
@@ -606,3 +617,28 @@ function queueDeferredWork(workId) {
         GLib.Source.set_name_by_id(_deferredTimeoutId, '[gnome-shell] _runAllDeferredWork');
     }
 }
+
+const RestartMessage = new Lang.Class({
+    Name: 'RestartMessage',
+    Extends: ModalDialog.ModalDialog,
+
+    _init : function(message) {
+        this.parent({ shellReactive: true,
+                      styleClass: 'restart-message',
+                      shouldFadeIn: false,
+                      destroyOnClose: true });
+
+        let label = new St.Label({ text: message });
+
+        this.contentLayout.add(label, { x_fill: false,
+                                        y_fill: false,
+                                        x_align: St.Align.MIDDLE,
+                                        y_align: St.Align.MIDDLE });
+        this.buttonLayout.hide();
+    }
+});
+
+function showRestartMessage(message) {
+    let restartMessage = new RestartMessage(message);
+    restartMessage.open();
+}