No webPreferences and session in e.sender received from an extension background page

[sentialx]

Preflight Checklist

• I have read the Contributing Guidelines for this project.
• I agree to follow the Code of Conduct that this project adheres to.
• I have searched the issue tracker for an issue that matches the one I want to file, without success.

Ref #19447

Issue Details

• Electron Version:
  • 9.0.0-beta.24
• Operating System:
  • macOS 10.15, Windows 10
• Last Known Working Electron version:
  • none

Expected Behavior

e.sender object received from an extension background page should have webPreferences and session initialized. It looks like options in api::WebContents constructor don't get initialized properly for an extension background page.

Actual Behavior

e.sender object doesn't have session and e.sender.getWebPreferences() returns null.

To Reproduce

https://github.com/sentialx/electron-quick-start/tree/extensions/no-session

Just run it and you will see something like this:

Additional Information

This is a real blocker for anyone who would want to provide own chrome APIs in background pages initialized from different sessions.

[nornagon]

Seems like this constructor isn't setting the session_ variable, so maybe that's the issue?