Merge "Fix NPE in BootReceiver.addTombstoneToDropBox." into sc-qpr1-dev am: 94d3762fba am: a28c22fc1c am: 2cfe38283f

Original change: https://googleplex-android-review.googlesource.com/c/platform/frameworks/base/+/15857254

Change-Id: Ie9085ced51942a59d05f2ef8361ab32710b93c0a