DO NOT MERGE: Add a checker for signature boundary in verifier am: f616da17...

DO NOT MERGE: Add a checker for signature boundary in verifier am: f616da17 am: 5346da02  -s ours am: a41cc294  -s ours am: 051dfa7e  -s ours am: 94c8b5e5 am: 2b1bcab4  -s ours am: 37a59414 am: ddca75fb am: b21b92b3 am: 8a513340  -s ours am: 67b69c05 am: 8f9e3c9b am: 8953f919
am: d0bfa33c

Change-Id: I73459eeb26653773edcf10209531f397e40d2c03