[chromedriver] When launching a Chrome App, automatically switch to the new window.

chrome/test/data/chromedriver/test_app/background.js

Index: chrome/test/data/chromedriver/test_app/background.js
diff --git a/chrome/test/data/extensions/platform_apps/web_view/dom_storage_isolation/main.js b/chrome/test/data/chromedriver/test_app/background.js
similarity index 71%
copy from chrome/test/data/extensions/platform_apps/web_view/dom_storage_isolation/main.js
copy to chrome/test/data/chromedriver/test_app/background.js
index 393037c6b7952c9d1c474c84f891423fab1fec90..7d921052f95c40baefb612f18f133f39c5ecf275 100644
--- a/chrome/test/data/extensions/platform_apps/web_view/dom_storage_isolation/main.js
+++ b/chrome/test/data/chromedriver/test_app/background.js
@@ -2,12 +2,11 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-function createWindow() {
+chrome.app.runtime.onLaunched.addListener(function() {
   chrome.app.window.create('window.html', {
     'bounds': {
       'width': 400,
-      'height': 400
+      'height': 500
     }
   });
-}
-chrome.app.runtime.onLaunched.addListener(createWindow);
+});