- 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
const content::WebContents* web_contents) {
  auto context = web_contents->GetBrowserContext();
  auto site_instance = web_contents->GetSiteInstance();
  if (!context || !site_instance)
    return nullptr;
  auto storage_partition =
      content::BrowserContext::GetStoragePartition(context, site_instance);
  if (!storage_partition)
    return nullptr;
  return storage_partition->GetServiceWorkerContext();
}
}  
WebContents::WebContents(content::WebContents* web_contents)
    : content::WebContentsObserver(web_contents),
      embedder_(nullptr),
      type_(REMOTE),
      request_id_(0),
      background_throttling_(true) {
  AttachAsUserData(web_contents);
  web_contents->SetUserAgentOverride(GetBrowserContext()->GetUserAgent());
}
WebContents::WebContents(v8::Isolate* isolate,
                         const mate::Dictionary& options)
    : embedder_(nullptr),
      request_id_(0),
      background_throttling_(true) {