[gnome-music] Don't duplicate request artwork

[Vadim Rutkovsky <vrutkovsky src gnome org>]

commit e42e66f272b924532870fe58bf2d0355ee691318
Author: Vadim Rutkovsky <vrutkovs redhat com>
Date:   Wed May 8 20:26:09 2013 +0200

    Don't duplicate request artwork
    
    As we're stripping symbols from album and artist names we're spamming server with
    multiple identical requests. The server stops accepting requests and the app hangs up.
    
    Fixed bug 699768

 src/albumArtCache.js |    4 ++++
 1 files changed, 4 insertions(+), 0 deletions(-)
---
diff --git a/src/albumArtCache.js b/src/albumArtCache.js
index 51454be..eabd911 100644
--- a/src/albumArtCache.js
+++ b/src/albumArtCache.js
@@ -37,6 +37,7 @@ const AlbumArtCache = new Lang.Class({
         this.parent();
         this.logLookupErrors = false;
 
+        this.requested_uris = [];
         this.cacheDir = GLib.build_filenamev([
             GLib.get_user_cache_dir(),
             "media-art"
@@ -104,6 +105,9 @@ const AlbumArtCache = new Lang.Class({
 
     getFromUri: function(uri, artist, album, width, height, callback) {
         if (uri == null) return;
+        if (this.requested_uris.indexOf(uri) > 0) return;
+
+        this.requested_uris.push(uri);
 
         let key = this._keybuilder_funcs[0].call(this, artist, album),
             path = GLib.build_filenamev([