Adds new rtc_* templates for Android targets to allow specifying default values that affect WebRTC targets. Bug: webrtc:6597 Change-Id: Ie529bfc8500d1e785b8a59dba7078b5f88ccfcd1 Reviewed-on: https://webrtc-review.googlesource.com/15103 Reviewed-by: Patrik Höglund <phoglund@webrtc.org> Commit-Queue: Sami Kalliomäki <sakal@webrtc.org> Cr-Commit-Position: refs/heads/master@{#20567}