Change TaskManager test to be in line with new TabContents lifetime uncertainty when Prerendering.

chrome/test/data/prerender/prerender_page.html

 <html>
 <!-- 
 This test checks to make sure that a prerendered page is loaded.
 -->
 <head>
-<title>Prerender Plugin Delay Loading</title>
+<title>Prerender Page</title>
 
 <script>
 var pageWasPrerendered = false;
 
 // Make sure plugin was not loaded while prerendering.
 function DidPrerenderPass() {
   pageWasPrerendered = true;
   return true;
 }
 
 // Make sure DidPrerenderPass() was called first.  Otherwise, the page was
 // most likely reloaded instead of using the prerendered page.
 function DidDisplayPass() {
   return pageWasPrerendered;
 }
 </script>
 
 </head>
 <body></body>
 </html>