Merge "Add null checks to browser callbacks" into rvc-dev am: 31a8993720 am: 8033376766 am: f1381e3ff9

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

Change-Id: I7734c3a5864453c78919d0d83493042a11d2a5d0