[HBD] Intercept Flash navigations in popup windows.

chrome/test/data/permissions/flash.js

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 function triggerPrompt() {
   document.getElementById('flash-link').click();
   window.domAutomationController.send(true);
 }
 
 function triggerPromptViaNewWindow() {
@@ skipping 14 matching lines @@
     window.domAutomationController.send(false);
 }
 
 function flashIsEnabled() {
   flashIsEnabledForPlugin(document.getElementById('flash-object'));
 }
 
 function flashIsEnabledForPluginWithoutFallback() {
   flashIsEnabledForPlugin(
       document.getElementById('flash-object-no-fallback'));
-}
+}
+
+function spawnPopupAndAwaitLoad() {
+  var popup = window.open(window.location.href);
+  popup.addEventListener('load', function handleLoad() {
+    popup.removeEventListener('load', handleLoad);
+    window.domAutomationController.send(true);
+  });
+}