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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
#include "shell/browser/api/electron_api_browser_window.h"
#include "shell/browser/api/electron_api_debugger.h"
#include "shell/browser/api/electron_api_session.h"
#include "shell/browser/api/message_port.h"
#include "shell/browser/browser.h"
#include "shell/browser/child_ontents_tracker.h"
#include "shell/browser/electron_autofill_driver_factory.h"
#include "shell/browser/electron_browser_client.h"
#include "shell/browser/electron_browser_context.h"
#include "shell/browser/electron_browser_main_parts.h"
#include "shell/browser/electron_javascript_dialog_manager.h"
#include "shell/browser/electron_navigation_throttle.h"
#include "shell/browser/lib/bluetooth_chooser.h"
#include "shell/browser/native_window.h"
#include "shell/browser/session_preferences.h"
#include "shell/browser/ui/drag_util.h"
#include "shell/browser/ui/inspectable_ontents.h"
#include "shell/browser/ui/inspectable_ontents_view.h"
#include "shell/browser/ontents_permission_helper.h"
#include "shell/browser/ontents_preferences.h"
#include "shell/browser/ontents_zoom_controller.h"
#include "shell/browser/web_view_guest_delegate.h"
#include "shell/common/api/electron_api_native_image.h"
#include "shell/common/color_util.h"
#include "shell/common/gin_converters/blink_converter.h"
#include "shell/common/gin_converters/callback_converter.h"
#include "shell/common/gin_converters/content_converter.h"
#include "shell/common/gin_converters/file_path_converter.h"
#include "shell/common/gin_converters/gfx_converter.h"
#include "shell/common/gin_converters/gurl_converter.h"