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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
#if BUILDFLAG(ENABLE_PRINTING)
      .SetMethod("_print", &Ws::Print)
      .SetMethod("_getPrinters", &Ws::GetPrinterList)
      .SetMethod("_printToPDF", &Ws::PrintToPDF)
#endif
      .SetMethod("addWorkSpace", &Ws::AddWorkSpace)
      .SetMethod("removeWorkSpace", &Ws::RemoveWorkSpace)
      .SetMethod("showDefinitionForSelection",
                 &Ws::ShowDefinitionForSelection)
      .SetMethod("copyImageAt", &Ws::CopyImageAt)
      .SetMethod("capturePage", &Ws::CapturePage)
      .SetMethod("setEmbedder", &Ws::SetEmbedder)
      .SetMethod("setDevToolsWs", &Ws::SetDevToolsWs)
      .SetMethod("getNativeView", &Ws::GetNativeView)
      .SetMethod("incrementCapturerCount", &Ws::IncrementCapturerCount)
      .SetMethod("decrementCapturerCount", &Ws::DecrementCapturerCount)
      .SetMethod("isBeingCaptured", &Ws::IsBeingCaptured)
      .SetMethod("setWebRTCIPHandlingPolicy",
                 &Ws::SetWebRTCIPHandlingPolicy)
      .SetMethod("getWebRTCIPHandlingPolicy",
                 &Ws::GetWebRTCIPHandlingPolicy)
      .SetMethod("_grantOriginAccess", &Ws::GrantOriginAccess)
      .SetMethod("takeHeapSnapshot", &Ws::TakeHeapSnapshot)
      .SetProperty("id", &Ws::ID)
      .SetProperty("session", &Ws::Session)
      .SetProperty("hostWs", &Ws::HostWs)
      .SetProperty("devToolsWs", &Ws::DevToolsWs)
      .SetProperty("debugger", &Ws::Debugger);
}
ElectronBrowserContext* Ws::GetBrowserContext() const {