AccessibilityNodeInfo.FindAccessibilityNodeInfosByViewId(..) returns
null when the source package is a supported browser, return a null
uri to prevent overwriting the existing notification's pendingIntent
uri extra with the brower's packageName.
* AccessibilityService.cs: Added null uri checks as it is now possible
for AccessibilityHelpers.getUri(..) to return a null uri when the
Accessibility Service is misbehaving.
c33728d418