Add Throbber control for DOMUI. Use it everywhere in options and in Sync setup UI.

chrome/browser/resources/options/import_data_overlay.js

Index: chrome/browser/resources/options/import_data_overlay.js
diff --git a/chrome/browser/resources/options/import_data_overlay.js b/chrome/browser/resources/options/import_data_overlay.js
index 0b7ebab9ea34c3def4562aa0988b593da7929ef2..a530b06fa4eb7c80fbe0547c27a2c383e27b5827 100644
--- a/chrome/browser/resources/options/import_data_overlay.js
+++ b/chrome/browser/resources/options/import_data_overlay.js
@@ -18,8 +18,6 @@ cr.define('options', function() {
                      'import-data-overlay');
   }
 
-  ImportDataOverlay.throbIntervalId = 0;
-
   cr.addSingletonGetter(ImportDataOverlay);
 
   ImportDataOverlay.prototype = {
@@ -60,6 +58,8 @@ cr.define('options', function() {
         ImportDataOverlay.dismiss();
       };
 
+      cr.ui.Throbber.decorate($('import-throbber'));
+
       // Form controls are disabled until the profile list has been loaded.
       self.setControlsSensitive_(false);
     },
@@ -167,19 +167,7 @@ cr.define('options', function() {
     }
     $('import-browsers').disabled = state;
     $('import-data-commit').disabled = state;
-    $('import-throbber').style.visibility = state ? "visible" : "hidden";
-
-    function advanceThrobber() {
-      var throbber = $('import-throbber');
-      throbber.style.backgroundPositionX =
-          ((parseInt(getComputedStyle(throbber).backgroundPositionX, 10) - 16)
-          % 576) + 'px';
-    }
-    if (state) {
-      ImportDataOverlay.throbIntervalId = setInterval(advanceThrobber, 30);
-    } else {
-      clearInterval(ImportDataOverlay.throbIntervalId);
-    }
+    $('import-throbber').visible = state;
   };
 
   /**