Add sent framerates to histogram stats:
"WebRTC.Video.InputFramesPerSecond",
"WebRTC.Video.SentFramesPerSecond".

BUG=488243
R=pbos@webrtc.org, stefan@webrtc.org

Review URL: https://codereview.webrtc.org/1169543005.

Cr-Commit-Position: refs/heads/master@{#9446}
3 files changed