[Sync] - In about:sync page display if the first sync after restart has taken place or not.

chrome/browser/resources/sync_internals/about.html

 <script src="chrome://sync-internals/about.js"></script>
 
 <style>
 div.column {
   display: inline-block;
   padding-right: 5em;
   vertical-align: top;
 }
 
 div#aboutInfo h2 {
@@ skipping 34 matching lines @@
   -webkit-animation-duration: 3s;
   -webkit-animation-timing-function: linear;
 }
 
 </style>
 
 <div id='aboutInfo'>
 <div class="column">
   <h2>Summary</h2>
   <p jscontent="summary"/>
+  <p jsdisplay="summary_explanation_needed">
+    <span class="err" jscontent="summary_explanation_message"></span>
+  </p>  
   <p jsdisplay="unrecoverable_error_detected">
     <span class="err" jscontent="unrecoverable_error_message"></span>
   </p>
 
   <p jsdisplay="failed_data_types">
     <span class="err" jscontent="failed_data_types"></span>
   </p>
 
   <h2>Sync URL</h2>
   <p jscontent="service_url"/>
@@ skipping 35 matching lines @@
 <div class="column">
   <h2>Actionable Error</h2>
   <table id="actionableError">
     <tr jsselect="actionable_error">
       <td jscontent="stat_name"/>
       <td jscontent="stat_value"/>
     </tr>
   </table>
 </div>
 </div>