Changed the BUILD.gn file that was lacking some necessary items which caused Chromium to break. Original review: https://webrtc-codereview.appspot.com/52059005/ The revert of the original CL was commit 7a75415419cbd52d798f9226010e9190e1cbad53. BUG=webrtc:4741 R=henrik.lundin@webrtc.org Review URL: https://codereview.webrtc.org/1200833002. Cr-Commit-Position: refs/heads/master@{#9489}