MediaBrowserServiceCompat: Handle null results from the implementation

When a null result is sent to ResultWrapper from the implementation of
onLoadChildren and/or onLoadItem on API 23+, the result couldn't be passed
to the origin result object or NPE could be happened.

Bug: 31106294
Change-Id: Idd7e095c3475c2ad3e8cf8a0ce85ec2f38fc4d31
2 files changed