WebUI: Return focus to anchor element when cr-action-menu is closed.

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

Index: chrome/test/data/webui/cr_elements/cr_action_menu_test.js
diff --git a/chrome/test/data/webui/cr_elements/cr_action_menu_test.js b/chrome/test/data/webui/cr_elements/cr_action_menu_test.js
index 86cb9816021bb2615354eca30d2fcd3c2e4ef3b4..233b3ec167765320673481f5fc7b556fabd4b1d2 100644
--- a/chrome/test/data/webui/cr_elements/cr_action_menu_test.js
+++ b/chrome/test/data/webui/cr_elements/cr_action_menu_test.js
@@ -93,11 +93,22 @@ suite('CrActionMenu', function() {
     assertFalse(menu.open);
   });
 
-  test('close on Tab', function() {
-    menu.showAt(document.querySelector('#dots'));
-    assertTrue(menu.open);
-
-    MockInteractions.keyDownOn(menu, 'Tab', [], 'Tab');
-    assertFalse(menu.open);
+  /** @param {string} key The key to use for closing. */
+  function testFocusAfterClosing(key) {
+    return new Promise(function(resolve) {
+      var dots = document.querySelector('#dots');
+      menu.showAt(dots);
+      assertTrue(menu.open);
+
+      // Check that focus returns to the anchor element.
+      dots.addEventListener('focus', resolve);
+      MockInteractions.keyDownOn(menu, key, [], key);
+      assertFalse(menu.open);
+    });
+  }
+
+  test('close on Tab', function() { return testFocusAfterClosing('Tab'); });
+  test('close on Escape', function() {
+    return testFocusAfterClosing('Escape');
   });
 });