Telemetry Test for WebRTC Rendering.

Design doc: https://docs.google.com/document/d/1TX0NnT_xxvnRNDkw6P2kxunXyK_I8OChkLb4jehXR9I/edit

BUG=
CQ_EXTRA_TRYBOTS=tryserver.chromium.perf:linux_perf_bisect;tryserver.chromium.perf:mac_10_10_perf_bisect;tryserver.chromium.perf:win_perf_bisect;tryserver.chromium.perf:android_nexus5_perf_bisect

Committed: https://crrev.com/4db46d73b08de41f0d838408b9b79b8844769489
Cr-Commit-Position: refs/heads/master@{#353615}

Review URL: https://codereview.chromium.org/1254023003

Cr-Commit-Position: refs/heads/master@{#354111}
7 files changed