Merge "Fix a memory leak when decoding corrupted indexed PNGs. Commit to branch refs/heads/png-leak" into master-skia

https://skia.googlesource.com/skia/+/f45796ee0eb46c2d08a6d1547622043892c525eb

Change-Id: Ib2ebba3af904ccbe75022a064fa1aef8a4d3428a