GitLab

The target was renamed in GYP a while back
and in https://code.google.com/p/webrtc/source/detail?r=8117
for GN. This is the last reference left using the
'webrtc_base' target name.

TBR=tommi@chromium.org

Review URL: https://codereview.chromium.org/868573003

Cr-Commit-Position: refs/heads/master@{#313100}