WIP at https://chromium-review.googlesource.com/c/chromium/src/+/1193877

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/058085dc79716a97136893e7396b63ed7197ee4f

commit 058085dc79716a97136893e7396b63ed7197ee4f
Author: François Beaufort <beaufort.francois@gmail.com>
Date: Thu Aug 30 15:29:14 2018

Picture-in-Picture close button click decrements keep alive count.

This makes sure extension internal keep_alive_count counter decrement
when user clicks "Close" button on the Picture-in-Picture window.

Bug:  878743 

Change-Id: I4a82ba3e0fa3c3de7241e73352ced30e14c59ca1
Reviewed-on: https://chromium-review.googlesource.com/1193877
Reviewed-by: Bo <boliu@chromium.org>
Commit-Queue: François Beaufort <beaufort.francois@gmail.com>
Cr-Commit-Position: refs/heads/master@{#587591}
[modify] https://crrev.com/058085dc79716a97136893e7396b63ed7197ee4f/content/browser/media/media_web_contents_observer.cc
[modify] https://crrev.com/058085dc79716a97136893e7396b63ed7197ee4f/content/browser/web_contents/web_contents_impl.cc
[modify] https://crrev.com/058085dc79716a97136893e7396b63ed7197ee4f/content/browser/web_contents/web_contents_impl.h

Tried to reproduce the issue on Windows 10 on the reported version 70.0.3535.4 and unable to reproduce the issue by following the below steps.

1. Launched Chrome and the flag enable-picture-in-picture is enabled in chrome://flags.
2. Navigated to https://japacible.github.io/sandbox/index.html and entered PIP.
3. tried navigating to about:extensions-internals and can see the error 'Site can't be reached'.
Attached is the screen cast for reference.

fbeaufort@ Request you to check and confirm if anything is missed from our end in reproducing the issue.
Also request you to provide the extension where this issue can be reproducible and help us in verifying the fix on the latest M-70 build.

Thanks..

Deleted: 878743.mp4 1.0 MB

	878743.mp4 1.0 MB View Download

I've verified manually in Chrome 71.0.3544.0 that this was fixed. Thanks!