Remove broken ShellAppSystem API and all consumers

In commit 9bd22dc0, I introduced an API to load an arbitrary
.desktop file, not necessarily from the menu path.  It turns
out this function was broken because it created ShellApp instances
that were *different* from ones that were cached normally.

As far as I can tell, we didn't initially use it.  Then later
Util.spawnDesktop was created which used this function.

Remove this broken function and all callers; if we're loading
.desktop files from *outside* the menu path, we can look at
readding.

This patch also kills off Util.spawnDesktop in favor of callers
talking to ShellAppSystem directly, now that the latter reports
errors.

https://bugzilla.gnome.org/show_bug.cgi?id=644402

js/misc/util.js

@@ -55,20 +55,6 @@ function spawnCommandLine(command_line) {
     }
 }
 
-// spawnDesktop:
-// @id: a desktop file ID
-//
-// Spawns the desktop file identified by @id using startup notification,
-// etc, handling any errors that occur when trying to find or start
-// the program.
-function spawnDesktop(id) {
-    try {
-        trySpawnDesktop(id);
-    } catch (err) {
-        _handleSpawnError(id, err);
-    }
-}
-
 // trySpawn:
 // @argv: an argv array
 //
@@ -116,33 +102,6 @@ function trySpawnCommandLine(command_line) {
     trySpawn(argv);
 }
 
-// trySpawnDesktop:
-// @id: a desktop file ID
-//
-// Spawns the desktop file identified by @id using startup notification.
-// On error, throws an exception.
-function trySpawnDesktop(id) {
-    let app;
-
-    // shell_app_system_load_from_desktop_file() will end up returning
-    // a stupid error message if the desktop file doesn't exist, but
-    // that's the only case it returns an error for, so we just
-    // substitute our own error in instead
-    try {
-        app = Shell.AppSystem.get_default().load_from_desktop_file(id + '.desktop');
-    } catch (err) {
-        throw new Error(_("No such application"));
-    }
-
-    try {
-        app.launch();
-    } catch(err) {
-        // see trySpawn
-        err.message = err.message.replace(/.*\((.+)\)/, '$1');
-        throw err;
-    }
-}
-
 function _handleSpawnError(command, err) {
     let title = _("Execution of '%s' failed:").format(command);
     Main.notifyProblem(title, err.message);

js/ui/dateMenu.js

@@ -200,7 +200,8 @@ DateMenuButton.prototype = {
 
     _onPreferencesActivate: function() {
         this.menu.close();
-        Util.spawnDesktop('gnome-datetime-panel');
+        let app = Shell.AppSystem.get_default().get_app('gnome-datetime-panel.desktop');
+        app.activate(-1);
     },
 
     _onOpenCalendarActivate: function() {

js/ui/status/accessibility.js

@@ -91,7 +91,8 @@ ATIndicator.prototype = {
 
         this.menu.addMenuItem(new PopupMenu.PopupSeparatorMenuItem());
         this.menu.addAction(_("Universal Access Settings"), function() {
-            Util.spawnDesktop('gnome-universal-access-panel');
+            let app = Shell.AppSystem.get_default().get_app('gnome-universal-access-panel.desktop');
+            app.activate(-1);
         });
     },
 

js/ui/status/power.js

@@ -83,7 +83,8 @@ Indicator.prototype = {
         this.menu.addMenuItem(new PopupMenu.PopupSeparatorMenuItem());
 
         this.menu.addAction(_("Power Settings"),function() {
-            Util.spawnDesktop('gnome-power-panel');
+            let app = Shell.AppSystem.get_default().get_app('gnome-power-panel.desktop');
+            app.activate(-1);
         });
 
         this._proxy.connect('Changed', Lang.bind(this, this._devicesChanged));

js/ui/status/volume.js

@@ -64,7 +64,8 @@ Indicator.prototype = {
 
         this.menu.addMenuItem(new PopupMenu.PopupSeparatorMenuItem());
         this.menu.addAction(_("Sound Settings"), function() {
-            Util.spawnDesktop('gnome-sound-panel');
+            let app = Shell.AppSystem.get_default().get_app('gnome-sound-panel.desktop');
+            app.activate(-1);
         });
 
         this.actor.connect('scroll-event', Lang.bind(this, this._onScrollEvent));

js/ui/statusMenu.js

@@ -190,12 +190,14 @@ StatusMenuButton.prototype = {
 
     _onMyAccountActivate: function() {
         Main.overview.hide();
-        Util.spawnDesktop('gnome-user-accounts-panel');
+        let app = Shell.AppSystem.get_default().get_app('gnome-user-accounts-panel.desktop');
+        app.activate(-1);
     },
 
     _onPreferencesActivate: function() {
         Main.overview.hide();
-        Util.spawnDesktop('gnome-control-center');
+        let app = Shell.AppSystem.get_default().get_app('gnome-control-center.desktop');
+        app.activate(-1);
     },
 
     _onLockScreenActivate: function() {