Fix proper deps in BUILD.gn files.
This should make Chrome GN bots happy.

R=kjellander@webrtc.org
TBR=kjellander@webrtc.org
BUG=3768, 3770

Review URL: https://webrtc-codereview.appspot.com/31389004

git-svn-id: http://webrtc.googlecode.com/svn/trunk@7219 4adac7df-926f-26a2-2b94-8c16560cd09d