Correctly handle tab navigation in the app list.

chrome/test/data/extensions/platform_apps/custom_launcher_page/main.js

Index: chrome/test/data/extensions/platform_apps/custom_launcher_page/main.js
diff --git a/chrome/test/data/extensions/platform_apps/custom_launcher_page/main.js b/chrome/test/data/extensions/platform_apps/custom_launcher_page/main.js
index bd16ca65576c3e0474bc231c5557f4082119e43e..ce4fdc07ac7132465ed16042a902cded91dc09a0 100644
--- a/chrome/test/data/extensions/platform_apps/custom_launcher_page/main.js
+++ b/chrome/test/data/extensions/platform_apps/custom_launcher_page/main.js
@@ -31,4 +31,15 @@ function enableCustomLauncherPage() {
   });
 }
 
-chrome.test.sendMessage('Launched');
+document.addEventListener('DOMContentLoaded', function() {
+  chrome.test.sendMessage('Launched');
+});
+
+var textfield = document.getElementById('textfield');
+textfield.onfocus = function() {
+  chrome.test.sendMessage('textfieldFocused');
+};
+
+textfield.onblur = function() {
+  chrome.test.sendMessage('textfieldBlurred');
+};