[automerger] Rework thumbnail cleanup am: 0dc23f95a1 skipped: 75767d1e3c am: 6720ea0b94 am: 16ee12ac68 am: d08bb4b174 am: b3f50c9ccb  -s ours am: b50ae71d99  -s ours
am: 21e5aeefce  -s ours

Change-Id: Ib0d77d48f378c8fc345c3c50e2be8d41cd4b28db