[Extensions] Simplify Extension Keybinding API Tests

chrome/test/data/extensions/test_file_with_ctrl-d_keybinding.html

Index: chrome/test/data/extensions/test_file_with_ctrl-d_keybinding.html
diff --git a/chrome/test/data/extensions/test_file_with_ctrl-d_keybinding.html b/chrome/test/data/extensions/test_file_with_ctrl-d_keybinding.html
index a032c6889bda58cd4cdf71430e35db4bc0793c15..7848c98d621261aa9195a348b6550fa9d38e9e57 100644
--- a/chrome/test/data/extensions/test_file_with_ctrl-d_keybinding.html
+++ b/chrome/test/data/extensions/test_file_with_ctrl-d_keybinding.html
@@ -11,7 +11,8 @@ document.onkeydown = function(e) {
   if (e.keyCode == 17 || e.keyCode == 91 || e.keyCode == 93) {
     ctrlDown = true;
   } else if (String.fromCharCode(e.keyCode) == 'D' && ctrlDown) {
-    document.body.bgColor = "magenta";
+    window.domAutomationController.setAutomationId(0);
+    window.domAutomationController.send('web page received');
     return false;
   }
 };