[Cookie] Enforce Source Type for new cookies

The source of new cookies should not be kUnknown unless we are in a
test. Let's try to enforce this and see what shakes out.

Bug: 1482799
Change-Id: I1414177159b1d006d9126e276ac8ec97d1ad22d9
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/5391942
Commit-Queue: Chris Fredrickson <[email protected]>
Reviewed-by: Peter Boström <[email protected]>
Reviewed-by: Chris Fredrickson <[email protected]>
Auto-Submit: Ari Chivukula <[email protected]>
Cr-Commit-Position: refs/heads/main@{#1278556}
diff --git a/base/check_is_test.cc b/base/check_is_test.cc
index 0c5a625..da9cad8e 100644
--- a/base/check_is_test.cc
+++ b/base/check_is_test.cc
@@ -12,8 +12,8 @@
 }
 
 namespace base::internal {
-void check_is_test_impl() {
-  CHECK(g_this_is_a_test);
+void check_is_test_impl(base::NotFatalUntil fatal_milestone) {
+  CHECK(g_this_is_a_test, fatal_milestone);
 }
 }  // namespace base::internal