Fix rewinding bug in SkJpegCodec

Performing a sampled and/or subset decode will create some state
in SkJpegCodec.  If we fail to clean up this state properly,
subsequent decodes may try to reuse (and potentailly overflow)
the leftover memory.

BUG=skia:
GOLD_TRYBOT_URL= https://gold.skia.org/search?issue=2161593003

Review-Url: https://codereview.chromium.org/2161593003
2 files changed