Bring PartNameMap parser into line with spec.

It changes from being very forgiving to more strict. Treating it as a comma
separated list of mappings. Each mapping is parsed strictly and
rejected if there is any problem but invalid mappings have no impact
on other mappings in the list.

Bug: 805271
Change-Id: I3b58a229ce6a2cf3ab979975973a29d6c978a788
Reviewed-on: https://chromium-review.googlesource.com/c/1351318
Commit-Queue: Fergal Daly <fergal@chromium.org>
Reviewed-by: Hayato Ito <hayato@chromium.org>
Cr-Commit-Position: refs/heads/master@{#613892}
3 files changed