- Electron version: v0.37.5
- Operating system: Any

It would be useful if we can open DevTools choosing all of it's available position: detached, docked right or docked bottom.

The new API could be something like this:
# webContents.openDevTools([options])

Opens the devtools.
- options Object (optional)
  - mode String - ['detached' | 'right' | 'bottom'] . opens DevTools in specified position. Defaults to last used mode.
  - detach Boolean - opens DevTools in a new window (deprecated, use mode: 'detached')

atom/browser/api/atom_api_web_contents.cc
WebContentsPreferences::FromWebContents(web_contents());
  std::string color_name;
  if (web_preferences->web_preferences()->GetString(options::kBackgroundColor,
                                                    &color_name)) {
    view->SetBackgroundColor(ParseHexColor(color_name));
  } else {
    view->SetBackgroundColor(SK_ColorTRANSPARENT);
  }
  
  const auto host = static_cast<content::RenderWidgetHostImpl*>(
      view->GetRenderWidgetHost());
  host->disable_hidden_ = !background_throttling_;
}
void WebContents::DownloadURL(const GURL& url) {
  auto browser_context = web_contents()->GetBrowserContext();
  auto download_manager =
    content::BrowserContext::GetDownloadManager(browser_context);
  download_manager->DownloadUrl(
    content::DownloadUrlParameters::FromWebContents(web_contents(), url));
}
GURL WebContents::GetURL() const {
  return web_contents()->GetURL();
}
base::string16 WebContents::GetTitle() const {
  return web_contents()->GetTitle();
}
bool WebContents::IsLoading() const {
  return web_contents()->IsLoading();
}
bool WebContents::IsWaitingForResponse() const {