Rewrite BrowserTest.PageLanguageDetection to use a new tab instead of the one with about:blank.

chrome/test/data/extensions/api_test/tabs/basics/crud.html

Index: chrome/test/data/extensions/api_test/tabs/basics/crud.html
diff --git a/chrome/test/data/extensions/api_test/tabs/basics/crud.html b/chrome/test/data/extensions/api_test/tabs/basics/crud.html
index ad9e21e0ae9e198134f3831bfceabd3269dad1c3..1a5f4a9a238a02a1b09729091a8b52c71be18311 100644
--- a/chrome/test/data/extensions/api_test/tabs/basics/crud.html
+++ b/chrome/test/data/extensions/api_test/tabs/basics/crud.html
@@ -92,15 +92,13 @@ chrome.test.runTests([
     }));
   },
 
-  /* Sadly, this has also regressed. crbug.com/60802.
   function detectLanguage() {
     chrome.tabs.getAllInWindow(firstWindowId, pass(function(tabs) {
       chrome.tabs.detectLanguage(tabs[0].id, pass(function(lang) {
-        assertEq("en", lang);
+        assertEq("und", lang);
       }));
     }));
   },
-  */
 
   function windowCreate() {
     chrome.windows.create({type: "popup"}, pass(function(window) {