[MD settings] disable clear browsing data while it is running

chrome/test/data/webui/settings/privacy_page_test.js

Index: chrome/test/data/webui/settings/privacy_page_test.js
diff --git a/chrome/test/data/webui/settings/privacy_page_test.js b/chrome/test/data/webui/settings/privacy_page_test.js
index 106e361f9568aa6d275624b792d8c3e87879c51a..1c291d926cde81771cec445687eda75031be75d3 100644
--- a/chrome/test/data/webui/settings/privacy_page_test.js
+++ b/chrome/test/data/webui/settings/privacy_page_test.js
@@ -51,6 +51,7 @@ cr.define('settings_privacy_page', function() {
 
     /** @override */
     clearBrowsingData: function() {
+      cr.webUIListenerCallback('browsing-data-removing', true);
       this.methodCalled('clearBrowsingData');
       return this.clearBrowsingDataPromise_ !== null ?
           this.clearBrowsingDataPromise_ : Promise.resolve();
@@ -58,7 +59,9 @@ cr.define('settings_privacy_page', function() {
 
     /** @override */
     initialize: function() {
+      cr.webUIListenerCallback('browsing-data-removing', false);
       this.methodCalled('initialize');
+      return Promise.resolve();
     },
   };
 
@@ -105,6 +108,7 @@ cr.define('settings_privacy_page', function() {
         PolymerTest.clearBody();
         element = document.createElement('settings-clear-browsing-data-dialog');
         document.body.appendChild(element);
+        return testBrowserProxy.whenCalled('initialize');
       });
 
       teardown(function() { element.remove(); });
@@ -136,6 +140,7 @@ cr.define('settings_privacy_page', function() {
 
               // Simulate signal from browser indicating that clearing has
               // completed.
+              cr.webUIListenerCallback('browsing-data-removing', false);
               promiseResolver.resolve();
               // Yields to the message loop to allow the callback chain of the
               // Promise that was just resolved to execute before the