Extensions other users don’t unload on exit

[MarcoJanse]

## Description
Brave loads extensions for each user you defined in people, but they don’t clean up when you close the only the window of the specific user, unless you close all open Brave windows. Also some subframes of websites you opened under another person don't close on exit.

## Steps to Reproduce

1. Create more people in Brave under People/Manage People
2. Open some tabs in your primary user and browse to any public website
3. Open Brave Task Manager using [Shift]+[Esc]. You should see the tabs and the default loaded extensions, like Brave Rewards, and PDF Viewer.
4. Go to People and open Brave with another user you defined in step 1
5. Browse to one or two public websites using that person
6. Check Task manager again. Duplicate extensions and the other tabs you opened should be visible.
7. Close the browser of the second user.
8. Check task manager. ( [Shift]+[Esc] )

## Actual result:
Subframes that you opened under the other person will still be running, and you should also see duplicate extensions that are still running and consuming memory.

## Expected result:
The subframes and extensions that were loaded with the other person should close when closing that specific Brave window.

## Reproduces how often:
Every time I browse using multiple persons

## Brave version (brave://version info)
Version 0.62.51 Chromium: 73.0.3683.103 (Official Build) (64-bit)

### Reproducible on current release:
yes

### Website problems only:

• Does the issue resolve itself when disabling Brave Shields? = YES
• Is the issue reproducible on the latest version of Chrome? = NO

### Additional Information
Tested on Windows 10 Pro Version 1809. Build 17763.437

[srirambv]

Reproduced the extension process. Subframes from second window gets removed once the window is closed

[MarcoJanse]

The subframes looks to be more random. I ran in to this a couple of times with subframes from https://login.microsoftonline.com (Office 365) and https://azure.net (portal.azure.com). Just tried to reproduce this again and now the subframes get closed like they should.

[JuanFarias1]

Is this issue still up for grabs!

[bsclifton]

@JuanFarias1 absolutely! Check out our getting started guide here:
https://github.com/brave/brave-browser/wiki

Let me know if you have any questions 😄