WebUI: For cr-dialog, make Enter key ignore disabled or hidden buttons

chrome/test/data/webui/cr_elements/cr_dialog_test.js

Index: chrome/test/data/webui/cr_elements/cr_dialog_test.js
diff --git a/chrome/test/data/webui/cr_elements/cr_dialog_test.js b/chrome/test/data/webui/cr_elements/cr_dialog_test.js
index 062211dab7a69851e671a22d5af59beb846ca37f..662386298da49a77298781b31c88021b6d176d0d 100644
--- a/chrome/test/data/webui/cr_elements/cr_dialog_test.js
+++ b/chrome/test/data/webui/cr_elements/cr_dialog_test.js
@@ -69,6 +69,36 @@ suite('cr-dialog', function() {
     assertEquals(1, clickedCounter);
   });
 
+  test('enter ignores hidden and disabled action buttons', function() {
+    document.body.innerHTML = `
+      <dialog is="cr-dialog">
+        <div class="title">title</div>
+        <div class="body">
+          <button id="hidden" class="action-button" hidden>hidden</button>
+          <button class="action-button" disabled>disabled</button>
+          <button class="action-button" disabled hidden>disabled hidden</button>
+          <button id="active" class="action-button">active</button>
+        </div>
+      </dialog>`;
+
+    var dialog = document.body.querySelector('dialog');
+    var hiddenButton = document.body.querySelector('#hidden');
+    var actionButton = document.body.querySelector('#active');
+    dialog.showModal();
+
+    // MockInteractions triggers event listeners synchronously.
+    hiddenButton.addEventListener('click', function() {
+      throw new Error('Hidden button received a click.');

[dpapad, 2017/04/04 17:10:17]

Nit: Can we use assertNotReached() instead? We actually have two such functions
and (unfortunately) whichever gets defined last overwrites the previous
definitions (see links below).

https://cs.chromium.org/chromium/src/chrome/test/data/webui/test_api.js?q&l=940
https://cs.chromium.org/chromium/src/ui/webui/resources/js/assert.js?l=55

[tommycli, 2017/04/04 17:44:11]

Done. And I can confirm this fails the test if I remove the :not([hidden])
selector qualifier.

+    })
+    var clicked = false;
+    actionButton.addEventListener('click', function() {
+      clicked = true;
+    });
+
+    MockInteractions.keyEventOn(dialog, 'keypress', 13, undefined, 'Enter');
+    assertTrue(clicked);
+  });
+
   test('focuses [autofocus] instead of title when present', function() {
     document.body.innerHTML = `
       <dialog is="cr-dialog">