st-texture-cache: purge on resume

With the proprietary nvidia driver, textures get garbled on suspend,
so the texture cache needs to evict all textures in that situation.

js/ui/main.js

@@ -211,7 +211,11 @@ function _initializeUI() {
         return true;
     });
 
-    global.display.connect('gl-video-memory-purged', loadTheme);
+    global.display.connect('gl-video-memory-purged', () => {
+        let cache = St.TextureCache.get_default();
+        cache.clear();
+        loadTheme();
+    });
 
     // Provide the bus object for gnome-session to
     // initiate logouts.

src/st/st-texture-cache.c

@@ -105,6 +105,18 @@ st_texture_cache_class_init (StTextureCacheClass *klass)
                   G_TYPE_NONE, 1, G_TYPE_FILE);
 }
 
+/* Evicts all cached textures */
+void
+st_texture_cache_clear (StTextureCache *cache)
+{
+  GHashTableIter iter;
+  gpointer key;
+  gpointer value;
+
+  g_hash_table_remove_all (cache->priv->keyed_cache);
+  g_signal_emit (cache, signals[ICON_THEME_CHANGED], 0);
+}
+
 /* Evicts all cached textures for named icons */
 static void
 st_texture_cache_evict_icons (StTextureCache *cache)

src/st/st-texture-cache.h

@@ -52,6 +52,7 @@ typedef enum {
 } StTextureCachePolicy;
 
 StTextureCache* st_texture_cache_get_default (void);
+void st_texture_cache_clear (StTextureCache *cache);
 
 ClutterActor *
 st_texture_cache_load_sliced_image (StTextureCache *cache,