[automerger skipped] Add proto definition for boottime metrics am: 352c9f6fbc -s ours
am skip reason: Change-Id I26cbca3b6f2d9f990dde31ac0880272ac141ff36 with SHA-1 bc3ce006de is in history

Change-Id: I63cbdb6282d62c91ea7170c1dd5e000b4edc53a2