I can't find tests by the name of "cross-origin-test" or "same-origin-test" by using codesearch or manually trying to run a test with those names:
https://cs.chromium.org/search/?q=cross-origin-test.js&sq=package:chromium&type=cs
third_party/blink/tools/run_web_tests.py http/tests/devtools/isolated-code-cache/same-origin-test.js

Could you help me find those tests?

That cl got reverted. I am trying to reland it now by updating the expectations. Here is the cl: https://chromium-review.googlesource.com/c/chromium/src/+/1329561/2.

The following revision refers to this bug:
  https://chromium.googlesource.com/chromium/src.git/+/8164901d8d42f2c4ef636c3068350ce98940b97b

commit 8164901d8d42f2c4ef636c3068350ce98940b97b
Author: Lukasz Anforowicz <lukasza@chromium.org>
Date: Wed Nov 21 19:30:38 2018

Extend isolated-code-cache=[Slow] to the not-site-per-process suite.

Bug:  907402 , 902685
Change-Id: Ifa530668be9f322a2ae5d92692298c20f98da828
Reviewed-on: https://chromium-review.googlesource.com/c/1347089
Reviewed-by: Alex Moshchuk <alexmos@chromium.org>
Commit-Queue: Łukasz Anforowicz <lukasza@chromium.org>
Cr-Commit-Position: refs/heads/master@{#610156}
[modify] https://crrev.com/8164901d8d42f2c4ef636c3068350ce98940b97b/third_party/WebKit/LayoutTests/SlowTests
[modify] https://crrev.com/8164901d8d42f2c4ef636c3068350ce98940b97b/third_party/WebKit/LayoutTests/TestExpectations

 Issue 907402  has been merged into this issue.

mythria@ lukasza@ now that the test has been relanded, is this still an issue?

Yes, I think the test is still slow - see https://bugs.chromium.org/p/chromium/issues/detail?id=907402#c7 (which provides data from today and yesterday, which I think comes from *after* the test has been relanded, right?).