MD Settings; Lazy instantiate Clear Browsing Data dialog.

chrome/browser/resources/settings/privacy_page/privacy_page.js

 // Copyright 2015 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.
 
 /**
  * @fileoverview
  * 'settings-privacy-page' is the settings page containing privacy and
  * security settings.
  *
  * Example:
@@ skipping 20 matching lines @@
       notify: true,
     },
 
     /**
      * The current active route.
      */
     currentRoute: {
       type: Object,
       notify: true,
     },
+
+    /** @private */
+    showClearBrowsingDataDialog_: Boolean,
   },
 
   ready: function() {
     this.ContentSettingsTypes = settings.ContentSettingsTypes;
   },
 
   /** @private */
   onManageCertificatesTap_: function() {
 <if expr="use_nss_certs">
     this.$.pages.setSubpageChain(['manage-certificates']);
 </if>
 <if expr="is_win or is_macosx">
     settings.PrivacyPageBrowserProxyImpl.getInstance().
       showManageSSLCertificates();
 </if>
   },
 
   /** @private */
   onSiteSettingsTap_: function() {
     this.$.pages.setSubpageChain(['site-settings']);
   },
 
   /** @private */
   onClearBrowsingDataTap_: function() {
-    this.$.pages.querySelector('settings-clear-browsing-data-dialog').open();
+    this.showClearBrowsingDataDialog_ = true;
+  },
+
+  /**
+   * @param {!Event} event
+   * @private
+   */
+  onIronOverlayClosed_: function(event) {
+    if (Polymer.dom(event).rootTarget.tagName == 'SETTINGS-DIALOG')
+      this.showClearBrowsingDataDialog_ = false;
   },
 });