Adding my metrics ambassador, mpearson@

Mark, the proposal here isn't really so much about features/experiments, rather we're just interested in the ability to remotely control the value of a double. Purely for the speed / flexibility. Is this usage generally agreeable? 

Aside: MediaCapabilities may have separate uses for the classic finch experiment down the road. 

> Is this usage generally agreeable? 
Yes.

You probably want to use GetFieldTrialParamByFeatureAsDouble().

Thanks! I was on the fence about that vs 

base::StringToDouble(GetFieldTrialParamValue(...))

the trade off being this one doesn't require a _feature_ to be defined... I don't technically have a feature associated with my double. Thoughts?

We generally recommend people use features and trigger behavior off of features rather than use field trial names.  It's more flexible.

http://go/finch-feature-api

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/8d1cffce0a566b9d5f5ffedfb66185c9d31dcfde

commit 8d1cffce0a566b9d5f5ffedfb66185c9d31dcfde
Author: Mounir Lamouri <mlamouri@chromium.org>
Date: Tue Nov 27 23:51:51 2018

Media Capabilities: make the smooth threshold configurable via Finch.

Bug:  817136 
Change-Id: I225591b1c6fdcaf50475a1a81cc2f2d5445b9eb3
Reviewed-on: https://chromium-review.googlesource.com/c/1351908
Commit-Queue: Mounir Lamouri <mlamouri@chromium.org>
Reviewed-by: Chrome Cunningham <chcunningham@chromium.org>
Cr-Commit-Position: refs/heads/master@{#611426}
[modify] https://crrev.com/8d1cffce0a566b9d5f5ffedfb66185c9d31dcfde/media/base/media_switches.cc
[modify] https://crrev.com/8d1cffce0a566b9d5f5ffedfb66185c9d31dcfde/media/base/media_switches.h
[modify] https://crrev.com/8d1cffce0a566b9d5f5ffedfb66185c9d31dcfde/media/mojo/services/video_decode_perf_history.cc
[modify] https://crrev.com/8d1cffce0a566b9d5f5ffedfb66185c9d31dcfde/media/mojo/services/video_decode_perf_history.h
[modify] https://crrev.com/8d1cffce0a566b9d5f5ffedfb66185c9d31dcfde/media/mojo/services/video_decode_perf_history_unittest.cc