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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
void Ws::TitleWasSet(content::NavigationEntry* entry) {
  base::string16 final_title;
  bool explicit_set = true;
  if (entry) {
    auto title = entry->GetTitle();
    auto url = entry->GetURL();
    if (url.SchemeIsFile() && title.empty()) {
      final_title = base::UTF8ToUTF16(url.ExtractFileName());
      explicit_set = false;
    } else {
      final_title = title;
    }
  }
  for (ExtendedWsObserver& observer : observers_)
    observer.OnPageTitleUpdated(final_title, explicit_set);
  Emit("page-title-updated", final_title, explicit_set);
}
void Ws::DidUpdateFaviconURL(
    const std::vector<blink::mojom::FaviconURLPtr>& urls) {
  std::set<GURL> unique_urls;
  for (const auto& iter : urls) {
    if (iter->icon_type != blink::mojom::FaviconIconType::kFavicon)
      continue;
    const GURL& url = iter->icon_url;
    if (url.is_valid())
      unique_urls.insert(url);
  }
  Emit("page-favicon-updated", unique_urls);
}
void Ws::DevToolsReloadPage() {