GitLab

webrtc::RTCStats lives in the WebRTC repo and can't be directly
accessed from Blink. In content we implement blink::WebRTCStats and
friends to bridge this gap.

Work split up in smaller CLs. In a follow-up CL we will gather stats
in content's rtc_peer_connection_handler.cc using
webrtc::RTCStatsCollector and return the resulting stats to Blink
using [Web]RTCStats, this will include unittests.

BUG=chromium:627816

Review-Url: https://codereview.chromium.org/2319543002
Cr-Commit-Position: refs/heads/master@{#417553}