Truly ignore failures in skimage.

If the expectation is set to ignore failures, do not return a
negative 1 (indicating a failure) when a successful decode
does not match the expectation.

If the file could not be decoded at all, report this to the
user depending on the input expectations file:

No expectations:
Report failure. The user wanted to know if the file could be
decoded.

Expectations expected a valid result:
Report failure. The decode should have matched the result.

Empty expectations:
Print a message that the expectation was missing, but still
return success from skimage, since this is a newly added file
(i.e. it has no expectation yet).

Ignore failure:
Return success from skimage, since it is a known failure.

Update the self tests to ensure these behaviors.

R=epoger@google.com

Review URL: https://codereview.chromium.org/22293006

git-svn-id: http://skia.googlecode.com/svn/trunk@11790 2bbb7eff-a529-9590-31e7-b0007b416f81
8 files changed