Electron Releases

Description of Change

Seen as the win-x64 test shard crash in https://github.com/electron/electron/actions/runs/31624457326/job/94214475444 (Cannot replace file '...\trace.json' : FILE_ERROR_EXISTS followed by persistent-node.h:162 Debug check failed: IsCreationThread()).

• stopRecording(path): when Chromium's FileTraceDataEndpoint fails to rename the finished trace into place it destroys its completion closure on the thread pool without running it. That closure owns the gin_helper::Promise, which since #51386 is a cppgc::Persistent and must die on the creating thread — DCHECK in testing builds, unsynchronized persistent-region mutation in release. Wrap the closure in BindPostTaskToCurrentDefault so it is run and destroyed on the UI thread either way. (The promise stays pending on that path, as before; the endpoint gives us no failure signal.)
• StopTracing() dereferenced the optional path before checking it, so a failed temp-file creation would crash instead of rejecting.
• Spec: every test attempt now gets its own output file. A timed-out attempt can leave an endpoint still writing to trace.json; two endpoints finalizing the same path race on the rename, which is how CI reached the failure path above.

Reproduced locally by pointing stopRecording() at a non-empty directory: pre-fix binary dies on the same DCHECK, fixed binary logs the endpoint error and carries on, subsequent sessions still work.

Checklist

• I have built and tested this change
• I have filled out the PR description
• I have reviewed and verified the changes
• npm test passes (relevant subset of api-content-tracing-spec)

Release Notes

Notes: Fixed a potential crash in contentTracing.stopRecording() when the trace file could not be written to the requested path.