D:\src\chromium\src>out\rel\browser_tests --gtest_filter=NativeBindings/MessagingApiTest.MessagingInterstitial/0 --site-per-process
IMPORTANT DEBUGGING NOTE: each test is run inside its own process.
For debugging a test inside a debugger, use the
--gtest_filter=<your_test_name> flag along with either
--single_process (to run the test in one launcher/browser process) or
--single-process (to do the above, and also run Chrome in single-process mode).
Using sharding settings from environment. This is shard 0/1
Using 1 parallel jobs.
Note: Google Test filter = NativeBindings/MessagingApiTest.MessagingInterstitial/0
[==========] Running 1 test from 1 test case.
[----------] Global test environment set-up.
[----------] 1 test from NativeBindings/MessagingApiTest
[ RUN      ] NativeBindings/MessagingApiTest.MessagingInterstitial/0
[8628:8816:0416/080931.930:ERROR:install_util.cc(589)] Unable to create registry key HKLM\SOFTWARE\Policies\Chromium for reading result=2
[8628:10816:0416/080932.018:WARNING:discovery_network_list_win.cc(195)] Failed to open Wlan client handle: 1062
[8628:8816:0416/080932.030:WARNING:chrome_browser_main_win.cc(630)] Command line too long for RegisterApplicationRestart:  --gtest_also_run_disabled_tests --gtest_filter=NativeBindings/MessagingApiTest.MessagingInterstitial/0 --single_process --site-per-process --test-launcher-output="D:\src\tmp\scoped_dir14220_6229\results14220_16959\test_results.xml" --user-data-dir="D:\src\tmp\scoped_dir14220_6229\d14220_2214" --disable-offline-auto-reload --allow-legacy-extension-manifests --disable-renderer-backgrounding --no-first-run --no-default-browser-check --enable-logging=stderr --disable-default-apps --wm-window-animations-disabled --disable-component-update --test-type=browser --force-color-profile=srgb --disable-zero-browsers-open-for-tests --ipc-connection-timeout=30 --allow-file-access-from-files --dom-automation --log-gpu-control-list-decisions --disable-backgrounding-occluded-windows --disable-gl-drawing-for-tests --override-use-software-gl-for-tests --force-color-profile=srgb --disable-compositor-ukm-for-tests --enable-features=NativeCrxBindings,TestFeatureForBrowserTest1 --disable-features=NetworkPrediction,TestFeatureForBrowserTest2 --flag-switches-begin --flag-switches-end --restore-last-session about:blank
[8628:8816:0416/080933.852:INFO:CONSOLE(0)] "Unchecked runtime.lastError: Could not establish connection. Receiving end does not exist.", source: data:text/html;charset=utf-8,%3C!doctype%20html%3E%0A%3Chtml%20dir=%22ltr%22%20lang=%22en%22%3
...
[1/1] NativeBindings/MessagingApiTest.MessagingInterstitial/0 (TIMED OUT)


The timeout seems to happen only on Windows 10 (after looking at tryjobs results in https://crrev.com/c/981019)