+fbeaufort@ because he cares about the naming

It's true, I do care about the naming ;)

Safari uses both Picture in Picture and "Picture-in-Picture". See https://support.apple.com/en-us/ht206997
Vimeo on Safari uses "Picture-in-Picture".

Having two names of the same feature will make it harder for translators to get it right 100% time.

It is shortened as PiP not Pip.

I'd suggest having one consistent string "Picture-in-Picture" in Chrome.

fbeaufort -- I'm going to add you to the email thread to weigh in on this. :)

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/dff79111f3857be3ac9d61a2f3b1c1b95442a699

commit dff79111f3857be3ac9d61a2f3b1c1b95442a699
Author: Jennifer Apacible <apacible@chromium.org>
Date: Tue Jul 10 22:53:14 2018

[Picture in Picture] Update "Picture-in-Picture" strings per OS.

MacOS and other OS have slightly different formats, where:
- MacOS: "Picture in Picture"
- Non-MacOS: "Picture in picture"
- Instructional (non-menu/titles): "...picture-in-picture mode..."

Bug:  859670 
Change-Id: I424bb618b9b337bf944d2f082522b9539d25e43c
Reviewed-on: https://chromium-review.googlesource.com/1123321
Commit-Queue: apacible <apacible@chromium.org>
Reviewed-by: Mounir Lamouri <mlamouri@chromium.org>
Reviewed-by: Ken Rockot <rockot@chromium.org>
Cr-Commit-Position: refs/heads/master@{#573963}
[modify] https://crrev.com/dff79111f3857be3ac9d61a2f3b1c1b95442a699/chrome/app/generated_resources.grd
[modify] https://crrev.com/dff79111f3857be3ac9d61a2f3b1c1b95442a699/content/app/strings/content_strings.grd
[modify] https://crrev.com/dff79111f3857be3ac9d61a2f3b1c1b95442a699/third_party/WebKit/LayoutTests/media/controls/video-controls-overflow-menu-text.html
[modify] https://crrev.com/dff79111f3857be3ac9d61a2f3b1c1b95442a699/third_party/WebKit/LayoutTests/media/overflow-menu.js