Add chrome.windows.update({focused:true});

chrome/test/data/extensions/api_test/tabs/basics/test.js

 // tabs api test
 // browser_tests.exe --gtest_filter=ExtensionApiTest.Tabs
 
 // We have a bunch of places where we need to remember some state from one
 // test (or setup code) to subsequent tests.
 var firstWindowId = null;
 var secondWindowId = null;
 var firstTabIndex = null;
 var testTabId = null;
 
@@ skipping 422 matching lines @@
       assertTrue(!window.incognito);
       windowEventsWindow = window;
       chrome.tabs.getAllInWindow(window.id, pass(function(tabs) {
         assertEq(pageUrl("a"), tabs[0].url);
       }));
     });
 
     chrome.windows.create({"url": pageUrl("a")}, pass(function(tab) {}));
   },
 
+  function windowSetFocused() {
+    chrome.windows.getCurrent(function(oldWin) {
+      chrome.windows.create({}, function(newWin) {
+        assertTrue(newWin.focused);
+        chrome.windows.update(oldWin.id, {focused:true});
+        chrome.windows.get(oldWin.id, pass(function(oldWin2) {
+          assertTrue(oldWin2.focused);
+        }));
+      });
+    });
+  },
+
   /* TODO: Enable this test when crbug.com/28055 is fixed. This bug causes a
      newly created window not to be set as the current window, if
      Chrome was not the foreground window when the create call was made.
   function windowsOnFocusChanged() {
     chrome.windows.create({}, pass(function(window) {
       chrome.test.listenOnce(chrome.windows.onFocusChanged,
                              function(windowId) {
         assertEq(windowEventsWindow.id, windowId);
       });
       chrome.windows.remove(window.id);
     }));
   } */
 ]);