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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
.SetMethod("openDevTools", &Ws::OpenDevTools)
      .SetMethod("closeDevTools", &Ws::CloseDevTools)
      .SetMethod("isDevToolsOpened", &Ws::IsDevToolsOpened)
      .SetMethod("isDevToolsFocused", &Ws::IsDevToolsFocused)
      .SetMethod("enableDeviceEmulation", &Ws::EnableDeviceEmulation)
      .SetMethod("disableDeviceEmulation", &Ws::DisableDeviceEmulation)
      .SetMethod("toggleDevTools", &Ws::ToggleDevTools)
      .SetMethod("inspectElement", &Ws::InspectElement)
      .SetMethod("setIgnoreMenuShortcuts", &Ws::SetIgnoreMenuShortcuts)
      .SetMethod("setAudioMuted", &Ws::SetAudioMuted)
      .SetMethod("isAudioMuted", &Ws::IsAudioMuted)
      .SetMethod("isCurrentlyAudible", &Ws::IsCurrentlyAudible)
      .SetMethod("undo", &Ws::Undo)
      .SetMethod("redo", &Ws::Redo)
      .SetMethod("cut", &Ws::Cut)
      .SetMethod("copy", &Ws::Copy)
      .SetMethod("paste", &Ws::Paste)
      .SetMethod("pasteAndMatchStyle", &Ws::PasteAndMatchStyle)
      .SetMethod("delete", &Ws::Delete)
      .SetMethod("selectAll", &Ws::SelectAll)
      .SetMethod("unselect", &Ws::Unselect)
      .SetMethod("replace", &Ws::Replace)
      .SetMethod("replaceMisspelling", &Ws::ReplaceMisspelling)
      .SetMethod("findInPage", &Ws::FindInPage)
      .SetMethod("stopFindInPage", &Ws::StopFindInPage)
      .SetMethod("focus", &Ws::Focus)
      .SetMethod("isFocused", &Ws::IsFocused)
      .SetMethod("tabTraverse", &Ws::TabTraverse)
      .SetMethod("_send", &Ws::SendIPCMessage)
      .SetMethod("_postMessage", &Ws::PostMessage)