Extend clickable hint in ChromeVox

Change-Id: Id5bc5e4ad89882a10342b23a68db10d8b9872d4a
Reviewed-on: https://chromium-review.googlesource.com/c/1481905Reviewed-by: Jenny Zhang <jennyz@chromium.org>
Commit-Queue: David Tseng <dtseng@chromium.org>
Cr-Commit-Position: refs/heads/master@{#634448}

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

@@ -480,7 +480,13 @@ AutomationPredicate.checkable = function(node) {
  * @return {boolean}
  */
 AutomationPredicate.clickable = AutomationPredicate.match({
-  anyPredicate: [AutomationPredicate.button, AutomationPredicate.link],
+  anyPredicate: [
+    AutomationPredicate.button, AutomationPredicate.link,
+    (node) => {
+      return node.defaultActionVerb ==
+          chrome.automation.DefaultActionVerb.CLICK;
+    }
+  ],
   anyAttribute: {clickable: true}
 });