[Bug]: Chrome Beta (139+) does not support loading extensions with browser flags

[fungairino]

Version

1.153.1

Steps to reproduce

Run the current playwright extension tests against the chrome-beta channel and observe that the extension is never loaded into the browser.

Expected behavior

The extension is loaded in the chrome-beta browser.

Actual behavior

The extension is not loaded in the chrome-beta browser.

Additional context

The announcement that deprecates the browser feature flags here:
https://support.google.com/chrome/a/answer/7679408?hl=en&co=CHROME_ENTERPRISE._Product%3DChromeBrowser
Discussed here as well:
https://groups.google.com/a/chromium.org/g/chromium-extensions/c/1-g8EFx2BBY/m/S0ET5wPjCAAJ
https://groups.google.com/a/chromium.org/g/chromium-extensions/c/aEHdhDZ-V0E/m/UWP4-k32AgAJ

Is there another way to load extensions for playwright testing? Will we need to switch over to chrome for testing? It doesn't seem like it is currently supported by playwright and not currently planned: #23694

Environment

System:
    OS: macOS 15.5
    CPU: (12) arm64 Apple M2 Max
    Memory: 86.38 MB / 32.00 GB
  Binaries:
    Node: 22.14.0 - ~/.nvm/versions/node/v22.14.0/bin/node
    npm: 10.9.2 - ~/.nvm/versions/node/v22.14.0/bin/npm
  Languages:
    Bash: 3.2.57 - /bin/bash

[fungairino]

I would also recommend updating the documentation to reflect that extensions cannot be loaded in chrome.

playwright/docs/src/chrome-extensions-js-python.md

Line 9 in 98caf34

Extensions only work in Chrome / Chromium launched with a persistent context. Use custom browser args at your own risk, as some of them may break Playwright functionality.

[mxschmitt]

Would channel: 'chromium' work for you?

[fungairino]

We switched over to 'chromium' for now, but it does not give us the same level of confidence. We would like to continue testing against the same browser that our users are using to make sure that we catch any potential regressions in our changes, but also to catch any new ones that might be coming down the line from chrome itself before it starts impacting our users. Browser extensions are still in a pretty volatile space, so we want to be able to catch any browser-specific issues before our users do.