The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/21715f31b594a60d4dccc97866039332cc12ef2e

commit 21715f31b594a60d4dccc97866039332cc12ef2e
Author: Jennifer Apacible <apacible@chromium.org>
Date: Thu Mar 01 19:23:10 2018

[Picture in Picture] Disable context menu PIP command.

This is temporary while PIP is being wired up and worked to be more
stable through the media controls entry point.

The menu item is not removed because we intend to continue using it
and it is currently hidden behind a flag.

BUG:  817598 
Change-Id: I9156d81b40dd6c97e19c6eef3f5fbbe13e350639
Reviewed-on: https://chromium-review.googlesource.com/942305
Commit-Queue: apacible <apacible@chromium.org>
Reviewed-by: Istiaque Ahmed <lazyboy@chromium.org>
Cr-Commit-Position: refs/heads/master@{#540246}
[modify] https://crrev.com/21715f31b594a60d4dccc97866039332cc12ef2e/chrome/browser/renderer_context_menu/render_view_context_menu.cc

+fbeaufort@ who said he would have a look at this.

https://chromium-review.googlesource.com/950945 addresses this.

Hi, I am going to work on PIP in ChromeOS. I tried to find multiple videos in chrome browser but found "Picture-in-Picture" item in the context menu is disabled. It should because the cl https://chromium-review.googlesource.com/950945 added a restriction. Is there any chance that how can I make the restriction happy and then enable the "Picture-in-Picture" in the context menu?

I just want to try to test it in my own device and see whether I can start to do sth in ChromeOS part. Thanks.

You can play with this Chrome Extension that demonstrates the Picture-in-Picture API in Chrome: https://github.com/beaufortfrancois/picture-in-picture-chrome-extension