Remove navigator.vibrate without user gesture.

third_party/WebKit/LayoutTests/resources/user-gesture-utils.js

+/**
+ * Simulates a user click on the element with an ID of [elementID] on optional
+ * [event] for features to be allowed in embedded iframes. Eg., for vibrate:
+ * https://www.chromestatus.com/feature/5644273861001216.
+ */
+function simulateUserClick(elementID, event) {
+  if (window.eventSender) {
+    var element = document.getElementById(elementID);
+    if (event === undefined) {
+      eventSender.mouseMoveTo(element.offsetLeft + 2, element.offsetTop + 2);
+    } else {
+      eventSender.mouseMoveTo(element.offsetLeft + event.data.x + 2, element.offsetTop + event.data.x + 2);
+    }
+    eventSender.mouseDown();
+    eventSender.mouseUp();
+  }
+}
+