remoteSearch: support serialized GIcons

Since [1], GIO supports generic serialization and deserialization of a
GIcon into a GVariant. This is also implemented by GdkPixbuf and could be
used instead of our homegrown code for it.

This commit adds support to another 'icon' key in the metas dictionary
returned by applications for it. The previous 'gicon' and 'icon-data'
keys are still parsed and supported as before, but are now deprecated.

[1]
https://git.gnome.org/browse/glib/commit/?id=c16f914b40c749b938490a4e10a3c54ec1855c42

https://bugzilla.gnome.org/show_bug.cgi?id=698761

configure.ac

@@ -65,7 +65,7 @@ GOBJECT_INTROSPECTION_MIN_VERSION=0.10.1
 GJS_MIN_VERSION=1.35.4
 MUTTER_MIN_VERSION=3.8.1
 GTK_MIN_VERSION=3.7.9
-GIO_MIN_VERSION=2.35.0
+GIO_MIN_VERSION=2.37.0
 LIBECAL_MIN_VERSION=3.5.3
 LIBEDATASERVER_MIN_VERSION=3.5.3
 TELEPATHY_GLIB_MIN_VERSION=0.17.5

data/org.gnome.ShellSearchProvider2.xml

@@ -46,7 +46,7 @@
     <!--
         GetResultMetas:
         @identifiers: An array of result identifiers as returned by GetInitialResultSet() or GetSubsearchResultSet()
-        @metas: A dictionary describing the given search result, containing a human-readable 'name' (string), along with the result identifier this meta is for, 'id' (string). Optionally, either 'gicon' (a serialized GIcon) or 'icon-data' (raw image data as (iiibiiay) - width, height, rowstride, has-alpha, bits per sample, channels, data) can be specified if the result can be better served with a thumbnail of the content (such as with images). A 'description' field (string) may also be specified if more context would help the user find the desired result.
+        @metas: A dictionary describing the given search result, containing a human-readable 'name' (string), along with the result identifier this meta is for, 'id' (string). Optionally, 'icon' (a serialized GIcon as obtained by g_icon_serialize) can be specified if the result can be better served with a thumbnail of the content (such as with images). 'gicon' (a serialized GIcon as obtained by g_icon_to_string) or 'icon-data' (raw image data as (iiibiiay) - width, height, rowstride, has-alpha, bits per sample, channels, data) are deprecated values that can also be used for that purpose. A 'description' field (string) may also be specified if more context would help the user find the desired result.
 
         Return an array of meta data used to display each given result
     -->

js/ui/remoteSearch.js

@@ -187,7 +187,9 @@ const RemoteSearchProvider = new Lang.Class({
 
     createIcon: function(size, meta) {
         let gicon;
-        if (meta['gicon']) {
+        if (meta['icon']) {
+            gicon = Gio.icon_deserialize(meta['icon']);
+        } else if (meta['gicon']) {
             gicon = Gio.icon_new_for_string(meta['gicon']);
         } else if (meta['icon-data']) {
             let [width, height, rowStride, hasAlpha,
@@ -240,8 +242,12 @@ const RemoteSearchProvider = new Lang.Class({
         let metas = results[0];
         let resultMetas = [];
         for (let i = 0; i < metas.length; i++) {
-            for (let prop in metas[i])
+            for (let prop in metas[i]) {
-                metas[i][prop] = metas[i][prop].deep_unpack();
+                // we can use the serialized icon variant directly
+                if (prop != 'icon')
+                    metas[i][prop] = metas[i][prop].deep_unpack();
+            }
+
             resultMetas.push({ id: metas[i]['id'],
                                name: metas[i]['name'],
                                description: metas[i]['description'],