The switch role is checkable.

ChromeVox was ignoring the checkedStateChanged event because it didn't
think that event should apply to a 'switch' role. It was correctly
announcing the state, just not correctly announcing when it changed.

Bug: b/111353265
Change-Id: I77c420c00e90d31c78f86610df7a3713eede360f
Reviewed-on: https://chromium-review.googlesource.com/1185866Reviewed-by: Katie Dektar <katie@chromium.org>
Commit-Queue: Dominic Mazzoni <dmazzoni@chromium.org>
Cr-Commit-Position: refs/heads/master@{#585316}

chrome/browser/resources/chromeos/chromevox/cvox2/background/automation_predicate.js

@@ -457,7 +457,7 @@ AutomationPredicate.shouldIgnoreNode = function(node) {
  */
 AutomationPredicate.checkable = AutomationPredicate.roles([
   Role.CHECK_BOX, Role.RADIO_BUTTON, Role.MENU_ITEM_CHECK_BOX,
-  Role.MENU_ITEM_RADIO, Role.TOGGLE_BUTTON, Role.TREE_ITEM
+  Role.MENU_ITEM_RADIO, Role.SWITCH, Role.TOGGLE_BUTTON, Role.TREE_ITEM
 ]);
 
 /**