Gallery.app: Fix thumbnail update of the ribbon in the slide mode.

ui/file_manager/gallery/js/ribbon.js

Index: ui/file_manager/gallery/js/ribbon.js
diff --git a/ui/file_manager/gallery/js/ribbon.js b/ui/file_manager/gallery/js/ribbon.js
index 32aaacacb4463063ad777f716f949b9afd1143fe..76a351b2d7d8711bb21e2cbffde0e74cfff36012 100644
--- a/ui/file_manager/gallery/js/ribbon.js
+++ b/ui/file_manager/gallery/js/ribbon.js
@@ -344,13 +344,8 @@ Ribbon.prototype.setThumbnailImage_ = function(thumbnail, entry, metadata) {
  */
 Ribbon.prototype.onContentChange_ = function(event) {
   var url = event.item.getEntry().toURL();
-  if (event.oldEntry.toURL() !== url) {
+  if (event.oldEntry.toURL() !== url)
     this.remapCache_(event.oldEntry.toURL(), url);
-  } else {
-    delete this.renderCache_[url];
-    var index = this.dataModel_.indexOf(event.item);
-    this.renderThumbnail_(index);
-  }
 
   var thumbnail = this.renderCache_[url];
   if (thumbnail && event.metadata)