Give error-toast a duration argument

res/js/common.js

 /**
  * common.js is a set of common functions used across all of skiaperf.
  *
  * Everything is scoped to 'sk' except $$ and $$$ which are global since they
  * are used so often.
  *
  */
 
 /**
  * $$ returns a real JS array of DOM elements that match the CSS query selector.
@@ skipping 53 matching lines @@
     return null;
   }
 
   /**
    * errorMessage dispatches an event with the error message in it.
    *
    * See <error-toast-sk> for an element that listens for such events
    * and displays the error messages.
    *
    */
-  sk.errorMessage = function(message) {
+  sk.errorMessage = function(message, duration) {
     var detail = {
       message: message,
     }
+    detail.duration = duration;
     document.dispatchEvent(new CustomEvent('error-sk', {detail: detail, bubbles: true}));
   }
 
   /**
    * Importer simplifies importing HTML Templates from HTML Imports.
    *
    * Just instantiate an instance in the HTML Import:
    *
    *    importer = new sk.Importer();
    *
@@ skipping 739 matching lines @@
   // returns true iff the string starts with the given prefix
   if (!String.prototype.startsWith) {
     String.prototype.startsWith = function(searchString, position) {
       position = position || 0;
       return this.indexOf(searchString, position) === position;
     };
   }
 
   return sk;
 }();