MD Settings: Don't auto-close navigable dialogs on popstate.

chrome/browser/resources/settings/reset_page/reset_profile_dialog.html

 <link rel="import" href="chrome://resources/cr_elements/cr_dialog/cr_dialog.html">
 <link rel="import" href="chrome://resources/html/action_link.html">
 <link rel="import" href="chrome://resources/html/polymer.html">
 <link rel="import" href="chrome://resources/html/web_ui_listener_behavior.html">
 <link rel="import" href="chrome://resources/polymer/v1_0/iron-flex-layout/classes/iron-flex-layout.html">
 <link rel="import" href="chrome://resources/polymer/v1_0/paper-button/paper-button.html">
 <link rel="import" href="chrome://resources/polymer/v1_0/paper-checkbox/paper-checkbox.html">
 <link rel="import" href="chrome://resources/polymer/v1_0/paper-spinner/paper-spinner.html">
 <link rel="import" href="/reset_page/reset_browser_proxy.html">
 <link rel="import" href="/settings_shared_css.html">
 
 <dom-module id="settings-reset-profile-dialog">
   <link rel="import" type="css" href="chrome://resources/css/action_link.css">
   <template>
     <style include="settings-shared">
       .footer a {
         color: rgb(66, 133, 244);
         text-decoration: none;
         vertical-align: middle;
       }
 
       paper-spinner {
         margin: 0 8px;
       }
     </style>
-    <dialog is="cr-dialog" id="dialog">
+    <dialog is="cr-dialog" id="dialog" ignore-popstate>
       <div class="title">
         [[getPageTitle_(isTriggered_, triggeredResetToolName_)]]
       </div>
       <div class="body">
         <span>
           [[getExplanationText_(isTriggered_, triggeredResetToolName_)]]
           <a href="$i18nRaw{resetPageLearnMoreUrl}" target="_blank">
             $i18n{learnMore}
           </a>
         </span>
@@ skipping 13 matching lines @@
       <div class="footer">
         <paper-checkbox id="sendSettings"
             checked>$i18n{resetPageFeedback}</paper-checkbox>
         <a is="action-link"
             on-tap="onShowReportedSettingsTap_">$i18n{viewReportedSettings}</a>
       </div>
     </dialog>
   </template>
   <script src="reset_profile_dialog.js"></script>
 </dom-module>