In parser.{cc,h}, replace CHECK_OK_CUSTOM by CHECK_OK_VOID, as that's all we need.
Use this to convert all void* functions to void.

R=adamk@chromium.org, nikolaos@chromium.org
BUG=

Review-Url: https://codereview.chromium.org/2165513004
Cr-Commit-Position: refs/heads/master@{#37878}