[lightsoff] snap: Update yaml to use GNOME extension

[Robert Roth <robertroth src gnome org>]

commit b27afc5cffba53ad73502d652dc688e22b3a8394
Author: Heather Ellsworth <hellsworth gnome org>
Date:   Wed Sep 25 06:56:14 2019 +0000

    snap: Update yaml to use GNOME extension

 snap/snapcraft.yaml | 34 ++--------------------------------
 1 file changed, 2 insertions(+), 32 deletions(-)
---
diff --git a/snap/snapcraft.yaml b/snap/snapcraft.yaml
index 8c2d2ac..d7d1e42 100644
--- a/snap/snapcraft.yaml
+++ b/snap/snapcraft.yaml
@@ -18,20 +18,6 @@ passthrough:
   license: GPL-2.0+
   title: Lights Off
 
-plugs:
-  gnome-3-28-1804:
-    interface: content
-    target: $SNAP/gnome-platform
-    default-provider: gnome-3-28-1804
-  gtk-3-themes:
-    interface: content
-    target: $SNAP/data-dir/themes
-    default-provider: gtk-common-themes
-  icon-themes:
-    interface: content
-    target: $SNAP/data-dir/icons
-    default-provider: gtk-common-themes
-
 slots:
   # for GtkApplication registration
   lightsoff:
@@ -41,14 +27,11 @@ slots:
 
 apps:
   lightsoff:
-    command: desktop-launch snapcraft-preload lightsoff
+    command: usr/bin/lightsoff
+    extensions: [gnome-3-28]
     plugs:
-      - desktop
-      - desktop-legacy
       - gsettings
       - opengl
-      - unity7
-      - wayland
     desktop: usr/share/applications/org.gnome.LightsOff.desktop
     environment:
       GSETTINGS_SCHEMA_DIR: $SNAP/share/glib-2.0/schemas
@@ -62,20 +45,7 @@ parts:
       - gcc-multilib
       - g++-multilib
 
-  desktop-gnome-platform:
-    source: https://github.com/ubuntu/snapcraft-desktop-helpers.git
-    source-subdir: gtk
-    plugin: make
-    make-parameters: ["FLAVOR=gtk3"]
-    build-packages:
-      - build-essential
-      - libgtk-3-dev
-    override-build: |
-      snapcraftctl build
-      mkdir -pv $SNAPCRAFT_PART_INSTALL/gnome-platform
-
   lightsoff:
-    after: [desktop-gnome-platform]
     source: .
     source-type: git
     override-build: |