MD Settings: On Startup, extract dialog to its own file.

chrome/browser/resources/settings/on_startup_page/startup_urls_page.html

 <link rel="import" href="chrome://resources/html/polymer.html">
 <link rel="import" href="chrome://resources/html/util.html">
 <link rel="import" href="chrome://resources/html/web_ui_listener_behavior.html">
-<link rel="import" href="chrome://resources/polymer/v1_0/paper-input/paper-input.html">
-<link rel="import" href="chrome://md-settings/settings_dialog.html">
 <link rel="import" href="chrome://md-settings/settings_shared_css.html">
+<link rel="import" href="chrome://md-settings/on_startup_page/startup_url_dialog.html">
 <link rel="import" href="chrome://md-settings/on_startup_page/startup_urls_page_browser_proxy.html">
 
 <dom-module id="settings-startup-urls-page">
   <link rel="import" type="css" href="on_startup_shared.css">
   <template>
     <style include="settings-shared">
       .favicon-image {
         background-size: contain;
         background-repeat: no-repeat;
         height: 16px;
         width: 16px;
       }
     </style>
     <div class="list-frame vertical-list">
       <template is="dom-repeat" items="[[startupPages_]]">
         <div class="list-item">
           <div class="favicon-image"
               style="background-image: [[getIconSet_(item.url)]]">
           </div>
           <div class="middle">
             <div class="text-elide">[[item.title]]</div>
             <div class="text-elide secondary">[[item.url]]</div>
           </div>
           <iron-icon on-tap="onRemoveUrlTap_" icon="clear"></iron-icon>
         </div>
       </template>
       <div class="list-item list-button" id="addPage" on-tap="onAddPageTap_">
         $i18n{onStartupAddNewPage}
       </div>
-      <div class="list-item list-button" on-tap="onUseCurrentPagesTap_">
-        $i18n{onStartupUseCurrent}
-      </div>
+      <div class="list-item list-button" id="useCurrentPages"
+          on-tap="onUseCurrentPagesTap_">$i18n{onStartupUseCurrent}</div>
     </div>
-
-    <settings-dialog id="addUrlDialog">
-      <div class="title">$i18n{onStartupAddNewPage}</div>
-      <div class="body">
-        <paper-input class="flex" always-float-label id="newUrl"
-            label="$i18n{onStartupSiteUrl}" value="{{newUrl_}}">
-        </paper-input>
-      </div>
-      <div class="button-container">
-        <div class="action-buttons">
-          <paper-button class="cancel-button" on-tap="onCancelTap_"
-              id="cancel">$i18n{cancel}</paper-button>
-          <paper-button id="add" class="action-button" on-tap="onAddTap_"
-              disabled="[[!isNewUrlValid_]]">$i18n{add}</paper-button>
-        </div>
-      </div>
-    </settings-dialog>
+    <template is="dom-if" if="[[showStartupUrlDialog_]]" restamp>
+      <settings-startup-url-dialog></settings-startup-url-dialog>
+    </template>
   </template>
   <script src="startup_urls_page.js"></script>
 </dom-module>