port eac1b38d

Original Commit Message:
    This flag has been on by default for a while, along with
    FLAG_track_prototype_users which provides the prerequisite
    infrastructure. We are now sure that this is the direction
    we want to go in, so in order to simplify the code, this CL
    drops the respective flag-off code paths.

R=jkummerow@chromium.org, joransiu@ca.ibm.com, michael_dawson@ca.ibm.com, mbrandy@us.ibm.com
BUG=

Review-Url: https://codereview.chromium.org/2004173003
Cr-Commit-Position: refs/heads/master@{#36491}