* Reorder and rename members of FrameStatistic.
* Rename corresponding temp variables used in the summary calculations.
* Make Stats class less structy.
* Try to enforce consistent frame numbers at all times.
* Remove VideoProcessor::FrameInfo struct and use the Stats class
for keeping track of encode/decode start times, etc.
BUG=webrtc:6634
Review-Url: https://codereview.webrtc.org/3011923002
Cr-Commit-Position: refs/heads/master@{#19703}
8935d97f16