dgozman@ - could you please help verify if this test failure uncovers any product bugs (vs is a test-only issue that shouldn't impact first OOPIF launch via --isolate-extensions)?

This is a test for our extensions mechanism, which are whitelisted from site-per-process in production for now. I think it doesn't work just because whitelisting is done for chrome-devtools:// scheme, while layout tests use http.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/6bd0f3201a2bc6c1d30dfc8a5a23eeeaedf56e2b

commit 6bd0f3201a2bc6c1d30dfc8a5a23eeeaedf56e2b
Author: lukasza <lukasza@chromium.org>
Date: Tue May 03 16:26:14 2016

Triaging some of the remaining site-per-process layout test failures.

Most of the changes in this CL just moved test expectations around and
added comments with bug pointers.

One exception is that http/tests/appcache/remove-cache.html expectation
has been removed altogether:
- this test passes on the Site Isolation FYI
- flakiness is already called out in  https://crbug.com/518929 
- locally I see a failure with and without --site-per-process, but since
  the bots are happy we should just remove the exception I think

BUG= 582211 ,  608015 ,  608023 ,  606594 ,  607991 ,  607981 

Review-Url: https://codereview.chromium.org/1931143002
Cr-Commit-Position: refs/heads/master@{#391262}

[modify] https://crrev.com/6bd0f3201a2bc6c1d30dfc8a5a23eeeaedf56e2b/third_party/WebKit/LayoutTests/FlagExpectations/site-per-process

Deprecating component:Blink>LayoutTests, to use label Test=Layout instead.

Removing the test, extensions tests are testing this functionality now.