This is a follow up of https://codereview.webrtc.org/2888893002/. Bug: None Change-Id: Ia76903858c0a6f2801f14878980e18ae6d3b85e6 Reviewed-on: https://chromium-review.googlesource.com/646020 Reviewed-by: Karl Wiberg <kwiberg@webrtc.org> Commit-Queue: Minyue Li (BackIn2018March) <minyue@webrtc.org> Cr-Commit-Position: refs/heads/master@{#19644}