[automerger skipped] Require protobuf for build flags am: e3e84fc1 -s ours

am skip reason: Merged-In Ia33aae158d62c12666d97449cea0c02b60550a21 with SHA-1 8663122e is already in history

Original change: https://googleplex-android-review.googlesource.com/c/platform/build/+/27829755



Change-Id: I2667160145920c17b25f1cd946fb19dbee6f6707
Signed-off-by: Automerger Merge Worker <android-build-automerger-merge-worker@system.gserviceaccount.com>