Enable GN check for webrtc/media
Enable GN check for webrtc/media

BUG=webrtc:6828, webrtc:7245
NOTRY=True

Review-Url: https://codereview.webrtc.org/2716143002
Cr-Original-Commit-Position: 972c6d2dc6dd5efdad1377c0d224e03eb8f276f7@{#17067}
Cr-Mirrored-From: https://chromium.googlesource.com/external/webrtc
Cr-Mirrored-Commit: a2ef4f94e478ac1eb8b3be47e63cdcd56cf66207

Alkalyne/webrtctrunk,Alkalyne/webrtctrunk,Alkalyne/webrtctrunk,Alkalyne/webrtctrunk,Alkalyne/webrtctrunk,Alkalyne/webrtctrunk,Alkalyne/webrtctrunk,Alkalyne/webrtctrunk