Files app: Use custom iron-iconset-svg for iron-icons.

ui/file_manager/file_manager/foreground/js/ui/combobutton.js

Index: ui/file_manager/file_manager/foreground/js/ui/combobutton.js
diff --git a/ui/file_manager/file_manager/foreground/js/ui/combobutton.js b/ui/file_manager/file_manager/foreground/js/ui/combobutton.js
index c2d639e7a0ee5f4a76a489212e066ca445790ab6..4e66457ce066c47153f4e076ffe110762d3216b5 100644
--- a/ui/file_manager/file_manager/foreground/js/ui/combobutton.js
+++ b/ui/file_manager/file_manager/foreground/js/ui/combobutton.js
@@ -82,7 +82,7 @@ cr.define('cr.ui', function() {
       buttonLayer.appendChild(this.actionNode_);
 
       var triggerIcon = this.ownerDocument.createElement('iron-icon');
-      triggerIcon.setAttribute('icon', 'arrow-drop-down');
+      triggerIcon.setAttribute('icon', 'files:arrow-drop-down');
       this.trigger_ = this.ownerDocument.createElement('div');
       this.trigger_.classList.add('trigger');
       this.trigger_.appendChild(triggerIcon);