Whenever we have an update to the sinks list, we re-draw all the list items. When this happens, the sink at the selected index has to be re-selected, and we do that with InkDrop::SnapToActivated() [1]. However this makes the color transition in a short animation shown in the attached video (you can see the top sink flicker twice). If you play the video slowly, you can see the ink drop color fading in gradually.

I looked into the InkDrop code but wasn't sure where the animation was coming from.
Bret, do you know of a way to fix this?

[1] https://cs.chromium.org/chromium/src/chrome/browser/ui/views/media_router/cast_dialog_sink_button.cc?g=0&l=124

Deleted: screen_capture-12.ogv 235 KB

	screen_capture-12.ogv 235 KB View Download

Hmm... SnapToActivated shouldn't be causing any animation, so that looks like a bug to me. I just clicked through all the implementations of SnapToActivated and nothing jumped out at me, so it probably needs a deeper investigation.

I wonder if there's some kind of "post-activated" state that's causing the animation?

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/5fb567371d3a6233c60e5d075091c68eed4f05ac

commit 5fb567371d3a6233c60e5d075091c68eed4f05ac
Author: Takumi Fujimoto <takumif@chromium.org>
Date: Thu May 31 00:13:40 2018

[Harmony Cast Dialog] Fix the flickering seen when updating sinks

This fixes the bug in which the selected sink's inkdrop color fades in
instead of snapping to cause a flickering effect.

Bug:  842792 
Change-Id: Ic4819552ee6a45f20c654a5ee4d9211b34f1f313
Reviewed-on: https://chromium-review.googlesource.com/1079695
Reviewed-by: Bret Sepulveda <bsep@chromium.org>
Commit-Queue: Takumi Fujimoto <takumif@chromium.org>
Cr-Commit-Position: refs/heads/master@{#563081}
[modify] https://crrev.com/5fb567371d3a6233c60e5d075091c68eed4f05ac/chrome/browser/ui/views/media_router/cast_dialog_sink_button.cc
[modify] https://crrev.com/5fb567371d3a6233c60e5d075091c68eed4f05ac/chrome/browser/ui/views/media_router/cast_dialog_sink_button.h