Problem: TestWebDriverSessionHistory flakes on slow (Sanitizer) CI
runners. The subtest checking that cancellation of a script-initiated
cross-site “back” by a beforeunload handler intermittently failed the
assertion “Expected beforeunload to cancel script-initiated cross-site
history.back(), got [url_b, 0]”. scriptBeforeUnloadCount was 0, not 1.
Cause: history.back() appends its traversal to the traversable’s session
history queue and returns immediately. So the beforeunload prompt to
unload runs async. The test read scriptBeforeUnloadCount in a separate
execute_script right after — with no wait. So on a slow runner, the read
beats the dispatch, and sees 0. Every other script-initiated navigation
in the test waits for its target document to load — and the “refresh”
beforeunload check already polls. But the canceled “back” loads no
target document — and this one waited for nothing.
Fix: Poll with wait_for_script_result until the page is still on /b and
window.scriptBeforeUnloadCount has incremented, before asserting the
final state — mirroring the “refresh” beforeunload check.
Problem: TestWebDriverSessionHistory failed intermittently on the slower
sanitizer CI runners. The UI history already matched what’s expected,
but webContentHistoryMatchesUI was still false — because the snapshot
was caught mid process-swap. The failing assertion varied from run to
run, making it almost certainly a sampling race.
Cause: A cross-site history navigation swaps the WebContent process and
re-seeds its history, and the UI-process mirror converges to that
asynchronously — after the script-visible navigation has finished. But
expect_ui_session_history sampled the mirror once, and asserted right
away — so it could read the state before convergence.
Fix: When a converged state is expected, wait for it instead of sampling
once: Poll until the UI history matches and WebContent matches the UI.
Keep UI process session history authoritative across overlapping
fallback loads and traversals. WebContent can finish a superseded
history load with a live document matching the UI seed URL while its
local step, document state id, and Navigation API keys still describe
a temporary partial list.
Reconstruct the current entry around the UI-owned list in that case.
This avoids making the UI process adopt WebContent's incomplete
snapshot.
Track UI-started fallback loads by URL so unrelated navigations cannot
consume the pending seed state. Resolve deferred WebDriver completions
through the view registry so callbacks queued before a process swap do
not touch a destroyed view.
Add WebDriver coverage that waits for explicit UI/WebContent history
convergence after the relevant document events. The waits poll
observable history state instead of depending on timing.
Wait for the WebDriver session history test to observe the UI-process
mirror after a same-document pushState setup before it starts testing a
browser UI history traversal.
The script-visible URL changes before the asynchronous session history
snapshot reaches the UI process, especially in sanitizer CI. The test
already needs the UI and WebContent histories to match at this point, so
wait for that condition directly instead of sampling the mirror at once.
Add a browser-driven WebDriver scenario for process swaps, renderer
crashes, nested frame history, reloads, and POST replacement cases. The
test drives the browser through the same UI-owned history paths used by
real back and forward actions.
Cover canceled navigations, javascript: no-op loads, source-document
traversal checks, and restored scroll state after crash recovery.
