- 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
return static_cast<AtomBrowserContext*>(web_contents()->GetBrowserContext());
}
void WebContents::OnRendererMessage(const base::string16& channel,
                                    const base::ListValue& args) {
  
  Emit(base::UTF16ToUTF8(channel), args);
}
void WebContents::OnRendererMessageSync(const base::string16& channel,
                                        const base::ListValue& args,
                                        IPC::Message* message) {
  
  EmitWithSender(base::UTF16ToUTF8(channel), web_contents(), message, args);
}
mate::Handle<WebContents> WebContents::CreateFrom(
    v8::Isolate* isolate, content::WebContents* web_contents) {
  
  auto existing = TrackableObject::FromWrappedClass(isolate, web_contents);
  if (existing)
    return mate::CreateHandle(isolate, static_cast<WebContents*>(existing));
  
  auto handle = mate::CreateHandle(isolate, new WebContents(web_contents));
  g_wrap_web_contents.Run(handle.ToV8());
  return handle;
}
mate::Handle<WebContents> WebContents::Create(