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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:
![image](https://user-images.githubusercontent.com/11065386/82097607-82994400-9703-11ea-8291-0eb987d8aca0.png)

### Additional Information
This is a real blocker for anyone who would want to provide own `chrome` APIs in background pages initialized from different sessions.
shell/browser/api/electron_api_web_contents.cc
bool stay_hidden = false;
   get stayHidden arguments if they exist
  args->GetNext(&stay_hidden);
  ontents()->DecrementCapturerCount(stay_hidden);
}
bool Ws::IsBeingCaptured() {
  return ontents()->IsBeingCaptured();
}
void Ws::OnCursorChanged(const content::WebCursor& webcursor) {
  const ui::Cursor& cursor = webcursor.cursor();
  if (cursor.type() == ui::mojom::CursorType::kCustom) {
    Emit("cursor-changed", CursorTypeToString(cursor),
         gfx::Image::CreateFrom1xBitmap(cursor.custom_bitmap()),
         cursor.image_scale_factor(),
         gfx::Size(cursor.custom_bitmap().width(),
                   cursor.custom_bitmap().height()),
         cursor.custom_hotspot());
  } else {
    Emit("cursor-changed", CursorTypeToString(cursor));
  }
}
bool Ws::IsGuest() const {
  return type_ == Type::WEB_VIEW;
}
void Ws::AttachToIframe(content::Ws* embedder_ontents,
                                 int embedder_frame_id) {
  if (guest_delegate_)
    guest_delegate_->AttachToIframe(embedder_ontents, embedder_frame_id);
}
bool Ws::IsOffScreen() const {