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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
int left = 0;
      margins.Get("left", &left);
      custom_margins.SetIntKey(printing::kSettingMarginLeft, left);
      int right = 0;
      margins.Get("right", &right);
      custom_margins.SetIntKey(printing::kSettingMarginRight, right);
      settings.SetPath(printing::kSettingMarginsCustom,
                       std::move(custom_margins));
    }
  } else {
    settings.SetIntKey(printing::kSettingMarginsType,
                       printing::DEFAULT_MARGINS);
  }
   Set whether to print color or greyscale
  bool print_color = true;
  options.Get("color", &print_color);
  int color_setting = print_color ? printing::COLOR : printing::GRAY;
  settings.SetIntKey(printing::kSettingColor, color_setting);
   Is the orientation landscape or portrait.
  bool landscape = false;
  options.Get("landscape", &landscape);
  settings.SetBoolKey(printing::kSettingLandscape, landscape);
   We set the default to the system's default printer and only update
   if at the Chromium level if the user overrides.
   Printer device name as opened by the OS.
  base::string16 device_name;
  options.Get("deviceName", &device_name);
  if (!device_name.empty() && !IsDeviceNameValid(device_name)) {
    args->ThrowError("ws.print(): Invalid deviceName provided.");
    return;