search: Replace 'icon' property in metaInfo with a function

Search results' meta info currently is expected to have an 'icon'
property holding a Clutter.Texture of a fixed icon size. This
property is used to implement the createIcon() function of BaseIcon,
which is used to actually display the result, ignoring the size
parameter due to the fixed icon size.
Given that all available search providers create this property for
the desired icon size using a function with the same signature, it
appears logical to replace the fixed-sized 'icon' property with
such a function, so that the icon size will be defined by the display
actor rather than the search system.

https://bugzilla.gnome.org/show_bug.cgi?id=643632

js/ui/appDisplay.js

@@ -251,7 +251,10 @@ BaseAppSearchProvider.prototype = {
             return null;
         return { 'id': resultId,
                  'name': app.get_name(),
-                 'icon': app.create_icon_texture(Search.RESULT_ICON_SIZE)};
+                 'createIcon': function(size) {
+                                   return app.create_icon_texture(size);
+                               }
+               };
     },
 
     activateResult: function(id, params) {

js/ui/docDisplay.js

@@ -26,7 +26,10 @@ DocSearchProvider.prototype = {
             return null;
         return { 'id': resultId,
                  'name': docInfo.name,
-                 'icon': docInfo.createIcon(Search.RESULT_ICON_SIZE)};
+                 'createIcon': function(size) {
+                                   return docInfo.createIcon(size);
+                               }
+               };
     },
 
     activateResult: function(id, params) {

js/ui/placeDisplay.js

@@ -415,7 +415,10 @@ PlaceSearchProvider.prototype = {
             return null;
         return { 'id': resultId,
                  'name': placeInfo.name,
-                 'icon': placeInfo.iconFactory(Search.RESULT_ICON_SIZE) };
+                 'createIcon': function(size) {
+                                   return placeInfo.iconFactory(size);
+                               }
+               };
     },
 
     activateResult: function(id, params) {

js/ui/search.js

@@ -15,8 +15,6 @@ const Main = imports.ui.main;
 
 const DISABLED_OPEN_SEARCH_PROVIDERS_KEY = 'disabled-open-search-providers';
 
-const RESULT_ICON_SIZE = 48;
-
 // Not currently referenced by the search API, but
 // this enumeration can be useful for provider
 // implementations.
@@ -165,8 +163,9 @@ SearchProvider.prototype = {
      * getResultInfo:
      * @id: Result identifier string
      *
-     * Return an object with 'id', 'name', (both strings) and 'icon' (Clutter.Texture)
-     * properties which describe the given search result.
+     * Return an object with 'id', 'name', (both strings) and 'createIcon'
+     * (function(size) returning a Clutter.Texture) properties which describe
+     * the given search result.
      */
     getResultMeta: function(id) {
         throw new Error('Not implemented');

js/ui/searchDisplay.js

@@ -36,9 +36,7 @@ SearchResult.prototype = {
                                    reactive: true,
                                    track_hover: true });
             let icon = new IconGrid.BaseIcon(this.metaInfo['name'],
-                                             { createIcon: Lang.bind(this, function(size) {
-                                                 return this.metaInfo['icon'];
-                                             })});
+                                             { createIcon: this.metaInfo['createIcon'] });
             content.set_child(icon.actor);
         }
         this._content = content;