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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("_sendToFrame", &Ws::SendIPCMessageToFrame)
      .SetMethod("sendInputEvent", &Ws::SendInputEvent)
      .SetMethod("beginFrameSubscription", &Ws::BeginFrameSubscription)
      .SetMethod("endFrameSubscription", &Ws::EndFrameSubscription)
      .SetMethod("startDrag", &Ws::StartDrag)
      .SetMethod("attachToIframe", &Ws::AttachToIframe)
      .SetMethod("detachFromOuterFrame", &Ws::DetachFromOuterFrame)
      .SetMethod("isOffscreen", &Ws::IsOffScreen)
#if BUILDFLAG(ENABLE_OSR)
      .SetMethod("startPainting", &Ws::StartPainting)
      .SetMethod("stopPainting", &Ws::StopPainting)
      .SetMethod("isPainting", &Ws::IsPainting)
      .SetMethod("setFrameRate", &Ws::SetFrameRate)
      .SetMethod("getFrameRate", &Ws::GetFrameRate)
#endif
      .SetMethod("invalidate", &Ws::Invalidate)
      .SetMethod("setZoomLevel", &Ws::SetZoomLevel)
      .SetMethod("getZoomLevel", &Ws::GetZoomLevel)
      .SetMethod("setZoomFactor", &Ws::SetZoomFactor)
      .SetMethod("getZoomFactor", &Ws::GetZoomFactor)
      .SetMethod("getType", &Ws::GetType)
      .SetMethod("_getPreloadPaths", &Ws::GetPreloadPaths)
      .SetMethod("getWebPreferences", &Ws::GetWebPreferences)
      .SetMethod("getLastWebPreferences", &Ws::GetLastWebPreferences)
      .SetMethod("getOwnerBrowserWindow", &Ws::GetOwnerBrowserWindow)
      .SetMethod("inspectServiceWorker", &Ws::InspectServiceWorker)
      .SetMethod("inspectSharedWorker", &Ws::InspectSharedWorker)
      .SetMethod("inspectSharedWorkerById",
                 &Ws::InspectSharedWorkerById)
      .SetMethod("getAllSharedWorkers", &Ws::GetAllSharedWorkers)