SurfaceFlinger: tune FPS detection logic

Keep 200ms of history for layer instead of 100ms to accomodate
scenarios of YouTube playing music and renders at ~6Hz.
In addition, change the way layers are considered relevant for fps
detection to have a time based mechanism as well. Going by frame number
only makes slow layers to become relevant too late.

Fixes: 135009095
Test: YouTube playing music
Change-Id: Id38290e453111c5cfd4a23383b36b6862c2dd386