Port 26ffee2c

Original commit message:
    It's just the same as StoreTransitionDescriptor.

R=mvstanton@chromium.org, dstence@us.ibm.com, michael_dawson@ca.ibm.com
BUG=

Review URL: https://codereview.chromium.org/1246143004

Cr-Commit-Position: refs/heads/master@{#29819}