[automerger] Fix overflow/dos in 3gg text description parsing am: 851e22d1...

[automerger] Fix overflow/dos in 3gg text description parsing am: 851e22d1 am: efeff077 am: 93e7dd1e am: 0d6a0e7d am: ec9f664d am: 806e1cbf am: e44b6c78 am: 6ea9da93 am: c17a483a am: 34b9e0b6
am: cd34f810

Change-Id: I292d3f0306197f7be105a38072f8f527d93cd508