The PRESUBMIT code is basically a stripped-down copy of the code in Chromium's src/PRESUBMIT.py. BUG=chromium:498746 TESTED=I verified with 'git cl presubmit' that the existing error was found. Then I ran it again after fixing it, with presubmit passing. NOTRY=True Review URL: https://codereview.webrtc.org/1682393002 Cr-Commit-Position: refs/heads/master@{#11572}