Recent failures on https://uberchromegw.corp.google.com/i/chromium.linux/builders/Linux%20Tests%20%28dbg%29%281%29?numbuilds=100

Example failure https://luci-logdog.appspot.com/v/?s=chromium%2Fbb%2Fchromium.linux%2FLinux_Tests__dbg__1_%2F62481%2F%2B%2Frecipes%2Fsteps%2Fbrowser_side_navigation_browser_tests%2F0%2Flogs%2FPageLoadMetricsBrowserTest.BadXhtml%2F0

[ RUN      ] PageLoadMetricsBrowserTest.BadXhtml
Xlib:  extension "RANDR" missing on display ":99".
[32508:32508:0418/171947.215494:WARNING:audio_manager.cc(293)] Multiple instances of AudioManager detected
[32508:32508:0418/171947.215640:WARNING:audio_manager.cc(254)] Multiple instances of AudioManager detected
[32508:32508:0418/171947.679883:WARNING:password_store_factory.cc(249)] 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.
[32508:32659:0418/171949.352443:WARNING:simple_synchronous_entry.cc(1054)] Could not open platform files for entry.
[32508:32685:0418/171949.899261:WARNING:embedded_test_server.cc(219)] Request not handled. Returning 404: /favicon.ico
[32508:32508:0418/171950.852706:ERROR:page_load_tracker.cc(232)] Invalid first_layout (unset) for first_paint 1.145 s
../../base/test/histogram_tester.cc:170: Failure
Value of: actual_count
  Actual: 2
Expected: expected_count
Which is: 1
Histogram "PageLoad.Internal.PageLoadTimingStatus" does not have the right total number of samples (1). It has (2).
[  FAILED  ] PageLoadMetricsBrowserTest.BadXhtml, where TypeParam =  and GetParam() =  (6606 ms)

Seems to have been flaking since build #62481
https://uberchromegw.corp.google.com/i/chromium.linux/builders/Linux%20Tests%20%28dbg%29%281%29/builds/62481

- but no obvious culprits in that blamelist.

I see it failing on builds 64481, 62489, 62499, 62501, 62504 (but not showing up as failed in results somehow), 62505, and passing otherwise.