Merge "Check DreamActivity callback type to prevent class cast exception" into tm-qpr-dev am: 8daaa631f2 am: 5984ded063

Original change: https://googleplex-android-review.googlesource.com/c/platform/frameworks/base/+/21938299

Change-Id: Ib664fa64eba67791cb08a1ea47f6423b5ca4d1ed
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>