The SiteDetailsBrowserTest.VerifySiteInstanceCountInBrowsingInstance test started failing flakily on the Site Isolation Linux FYI bot around this build:
https://build.chromium.org/p/chromium.fyi/builders/Site%20Isolation%20Linux/builds/8277

It's failing on an ASSERT added in https://codereview.chromium.org/1769683002, which landed in the build linked above.  dglazkov@, can you take a look?  That bot is just running the tests with --site-per-process.

Sample output:

SiteDetailsBrowserTest.VerifySiteInstanceCountInBrowsingInstance (run #1):
[ RUN      ] SiteDetailsBrowserTest.VerifySiteInstanceCountInBrowsingInstance
Xlib:  extension "RANDR" missing on display ":9".
Xlib:  extension "RANDR" missing on display ":9".
[15192:15192:0304/190240:WARNING:password_store_factory.cc(250)] Using basic (unencrypted) store for password storage. See https://chromium.googlesource.com/chromium/src/+/master/docs/linux_password_storage.md for more information about password storage options.
[15192:15241:0304/190240:ERROR:zygote_host_impl_linux.cc(162)] Failed to adjust OOM score of renderer with pid 15287: Permission denied
[15283:15283:0304/190240:WARNING:ipc_message_attachment_set.cc(57)] MessageAttachmentSet destroyed with unconsumed descriptors: 0/1
[15192:15241:0304/190241:ERROR:zygote_host_impl_linux.cc(162)] Failed to adjust OOM score of renderer with pid 15323: Permission denied
[15192:15241:0304/190241:ERROR:zygote_host_impl_linux.cc(162)] Failed to adjust OOM score of renderer with pid 15324: Permission denied
[15192:15241:0304/190241:ERROR:zygote_host_impl_linux.cc(162)] Failed to adjust OOM score of renderer with pid 15326: Permission denied
[15192:15241:0304/190241:ERROR:zygote_host_impl_linux.cc(162)] Failed to adjust OOM score of renderer with pid 15328: Permission denied
[15192:15241:0304/190241:ERROR:zygote_host_impl_linux.cc(162)] Failed to adjust OOM score of renderer with pid 15333: Permission denied
[15192:15241:0304/190241:ERROR:zygote_host_impl_linux.cc(162)] Failed to adjust OOM score of renderer with pid 15390: Permission denied
[15192:15241:0304/190241:ERROR:zygote_host_impl_linux.cc(162)] Failed to adjust OOM score of renderer with pid 15418: Permission denied
[15192:15241:0304/190241:ERROR:zygote_host_impl_linux.cc(162)] Failed to adjust OOM score of renderer with pid 15420: Permission denied
[15192:15310:0304/190242:WARNING:embedded_test_server.cc(167)] Request not handled. Returning 404: /favicon.ico
ASSERTION FAILED: !start.document()->needsLayoutTreeUpdate()
../../third_party/WebKit/Source/core/editing/iterators/TextIterator.cpp(153) : blink::TextIteratorAlgorithm<blink::EditingAlgorithm<blink::NodeTraversal> >::TextIteratorAlgorithm(const PositionTemplate<Strategy> &, const PositionTemplate<Strategy> &, TextIteratorBehaviorFlags) [Strategy = blink::EditingAlgorithm<blink::NodeTraversal>]
1   0x3821647
2   0x38214ad
3   0x5cd61a7
4   0x5922177
5   0x5959d83
6   0x38644df
7   0x58d5e04
8   0x26b9028
9   0x26c64f4
10  0x5c3e00c
11  0x5871c27
12  0x58708cf
13  0x5872c44
14  0x5c3e00c
15  0x5c5b58b
16  0x5c5b888
17  0x5c5ba3b
18  0x5c5d34f
19  0x5c5b0dc
20  0x5c7a4cc
21  0x5c5a410
22  0x5960e7e
23  0x5b5778b
24  0x5b57dc2
25  0x5b587eb
26  0x5b57350
27  0x5b7b4fb
28  0x121ec3a
29  0x5c03c9
30  0x7eff6231076d __libc_start_main
31  0x5c02c1
../../chrome/browser/site_details_browsertest.cc:1153: Failure
Value of: details->uma()->GetAllSamples( "SiteIsolation.SiteInstancesPerBrowsingInstance")
Expected: has 1 element that is a Bucket whose count is 1 and whose value is (under --site-per-process) 11
  Actual: {}
../../chrome/browser/site_details_browsertest.cc:1155: Failure
Value of: details->uma()->GetAllSamples("SiteIsolation.ProxyCount")
Expected: has 1 element that is a Bucket whose count is 1 and whose value is (under --site-per-process) 160
  Actual: { Bucket 0: 1 }, whose element #0 doesn't match
../../chrome/browser/site_details_browsertest.cc:1158: Failure
Value of: details->uma()->GetAllSamples( "SiteIsolation.ProxyCountPerBrowsingInstance")
Expected: has 1 element that is a Bucket whose count is 1 and whose value is (under --site-per-process) 160
  Actual: {}
[15192:15241:0304/190242:ERROR:zygote_host_impl_linux.cc(162)] Failed to adjust OOM score of renderer with pid 15546: Permission denied
[15192:15241:0304/190242:ERROR:zygote_host_impl_linux.cc(162)] Failed to adjust OOM score of renderer with pid 15562: Permission denied
[15192:15241:0304/190243:ERROR:zygote_host_impl_linux.cc(162)] Failed to adjust OOM score of renderer with pid 15609: Permission denied
[15192:15241:0304/190243:ERROR:zygote_host_impl_linux.cc(162)] Failed to adjust OOM score of renderer with pid 15649: Permission denied
../../chrome/browser/site_details_browsertest.cc:1171: Failure
Value of: details->uma()->GetAllSamples( "SiteIsolation.SiteInstancesPerBrowsingInstance")
Expected: (under --site-per-process) 16-byte object <0B-00 00-00 01-00 00-00 04-00 00-00 01-00 00-00>
  Actual: { Bucket 4: 1 }, which has 1 element
../../chrome/browser/site_details_browsertest.cc:1173: Failure
Value of: details->uma()->GetAllSamples("SiteIsolation.ProxyCount")
Expected: has 1 element that is a Bucket whose count is 1 and whose value is (under --site-per-process) 160
  Actual: { Bucket 12: 1 }, whose element #0 doesn't match
../../chrome/browser/site_details_browsertest.cc:1178: Failure
Value of: details->uma()->GetAllSamples( "SiteIsolation.ProxyCountPerBrowsingInstance")
Expected: (under --site-per-process) 16-byte object <A0-00 00-00 01-00 00-00 0C-00 00-00 01-00 00-00>
  Actual: { Bucket 12: 1 }, which has 1 element
[  FAILED  ] SiteDetailsBrowserTest.VerifySiteInstanceCountInBrowsingInstance, where TypeParam =  and GetParam() =  (3463 ms)