Loading Indicator for Distilled Pages

components/dom_distiller/content/resources/dom_distiller_viewer.js

 // Copyright 2014 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 function addToPage(html) {
   var div = document.createElement('div');
   div.innerHTML = html;
   document.getElementById('content').appendChild(div);
 }
 
 function showLoadingIndicator(isLastPage) {
   document.getElementById('loadingIndicator').className =
       isLastPage ? 'hidden' : 'visible';
+  updateLoadingIndicator(isLastPage);
 }
 
 // Maps JS theme to CSS class and then changes body class name.
 // CSS classes must agree with distilledpage.css.
 function useTheme(theme) {
   var cssClass;
   if (theme == "sepia") {
     cssClass = "sepia";
   } else if (theme == "dark") {
     cssClass = "dark";
   } else {
     cssClass = "light";
   }
   document.body.className = cssClass;
 }
+
+var updateLoadingIndicator = function() {
+  var colors = ["red", "yellow", "green", "blue"];
+  return function(isLastPage) {
+    if (!isLastPage && typeof this.colorShuffle == "undefined") {
+      var loader = document.getElementById("loader");
+      if (loader) {
+        var colorIndex = -1;
+        this.colorShuffle = setInterval(function() {
+          colorIndex = (colorIndex + 1) % colors.length;
+          loader.className = colors[colorIndex];
+        }, 600);
+      }
+    } else if (isLastPage && typeof this.colorShuffle != "undefined") {
+      clearInterval(this.colorShuffle);
+    }
+  };
+}();