Merge "Remove meaningless ActivityStarter#mReuseTask" into tm-dev am: 35a7d444 am: c9e2b11c

Original change: https://googleplex-android-review.googlesource.com/c/platform/frameworks/base/+/17536787



Change-Id: Ic2a5ba77dceaf308a7bb223bd6c1dae51f19876b
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>