fix: associate extHost lifecycle to window

[deepak1556]

Fixes #291346

With migration to render process reuse, our native-watchdog in the extension host cannot help with shutdown down of long running process on workbench reload. Instead we now rely on the main process to kill the extension host when the associated window is closed or reloaded.

[Copilot]

Pull request overview

This PR ties the Electron (main process) extension host utility process lifecycle to the owning window so that window reload/close reliably terminates long-running/blocked extension host processes, addressing #291346.

Changes:

• Bind extension host utility processes to the window lifecycle via windowLifecycleBound: true in the Electron main extension host starter.
• Add a new smoke test that blocks the extension host, reloads the window, and verifies the old extension host PID is terminated.
• Add a dedicated smoke test extension used by the new restart test and wire it into the smoke test runner.

Reviewed changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated 5 comments.

Show a summary per file

File	Description
src/vs/platform/extensions/electron-main/extensionHostStarter.ts	Binds the extension host utility process lifecycle to the owning window so reload/close kills it.
test/smoke/src/main.ts	Copies the new smoke-test extension into the test extensions dir and registers the new restart suite.
test/smoke/src/areas/extensions/extension-host-restart.test.ts	Adds a smoke test that blocks the extension host, reloads the window, and asserts the old PID is gone.
test/smoke/extensions/vscode-smoketest-ext-host/package.json	Declares the new smoke-test extension that exposes a command used to block the extension host.
test/smoke/extensions/vscode-smoketest-ext-host/extension.js	Implements the command to record the extension host PID and block execution.

[alexdima]

Nice! I just left a comment about the graceful 5s behavior we used to have

[vs-code-engineering]

📬 CODENOTIFY

The following users are being notified based on files changed in this PR:

@bpasero

Matched files:

• src/vs/platform/utilityProcess/electron-main/utilityProcess.ts