Merge "Add null checks to browser callbacks" into rvc-dev am: 31a8993720 am: 8033376766 am: d65412f3bf

Original change: https://googleplex-android-review.googlesource.com/c/platform/frameworks/base/+/12035628

Change-Id: I0176cd3b78987da172ce04927004a4122165b8fc