[gnome-sdk-images/theme-extensions] Define theme extensions

[Matthias Clasen <matthiasc src gnome org>]

commit 77a5abcc68f17d472a348e97bfde907e2735fba2
Author: Matthias Clasen <mclasen redhat com>
Date:   Fri Apr 14 23:32:33 2017 -0400

    Define theme extensions
    
    This adds two extensions, org.freedesktop.Platform.Icontheme and
    org.gnome.Platform.Gtk3theme. To avoid interference with the
    themes that are already included in the runtimes, we place
    these in /usr/share/runtime/share/{themes,icons}, and include
    /usr/share/runtime/share in XDG_DATA_DIRS.

 org.gnome.Sdk.json.in |   12 ++++++++++++
 1 files changed, 12 insertions(+), 0 deletions(-)
---
diff --git a/org.gnome.Sdk.json.in b/org.gnome.Sdk.json.in
index 369f781..74438b7 100644
--- a/org.gnome.Sdk.json.in
+++ b/org.gnome.Sdk.json.in
@@ -28,8 +28,16 @@
         "--extension=org.freedesktop.Sdk.Extension=directory=lib/sdk",
         "--extension=org.freedesktop.Sdk.Extension=no-autodownload=true",
         "--extension=org.freedesktop.Sdk.Extension=version=1.6",
+        "--extension=org.freedesktop.Platform.Icontheme=directory=share/runtime/share/icons",
+        "--extension=org.freedesktop.Platform.Icontheme=subdirectories=true",
+        "--extension=org.freedesktop.Platform.Icontheme=no-autodownload=true",
+        "--extension=org.gnome.Platform.Gtk3theme=directory=share/runtime/share/themes",
+        "--extension=org.gnome.Platform.Gtk3theme=subdirectories=true",
+        "--extension=org.gnome.Platform.Gtk3theme=subdirectory-suffix=gtk-3.0",
+        "--extension=org.gnome.Platform.Gtk3theme=no-autodownload=true",
         "--env=GI_TYPELIB_PATH=/app/lib/girepository-1.0",
         
"--env=GST_PLUGIN_SYSTEM_PATH=/app/lib/gstreamer-1.0:/usr/lib/extensions/gstreamer-1.0:/usr/lib/gstreamer-1.0",
+        "--env=XDG_DATA_DIRS=/app/share:/usr/share:/usr/share/runtime/share",
         "--sdk=org.gnome.Sdk//@@SDK_BRANCH@@",
         "--runtime=org.gnome.Platform//@@SDK_BRANCH@@"
     ],
@@ -881,6 +889,10 @@
         },
         {
             "name": "os-release",
+            "post-install": [
+                "mkdir -p /usr/share/runtime/share/themes",
+                "mkdir -p /usr/share/runtime/share/icons"
+            ],
             "sources": [
                 {
                     "type": "file",