- 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
if (IsDevToolsOpened())
    CloseDevTools();
  else
    OpenDevTools(nullptr);
}
void WebContents::InspectElement(int x, int y) {
  if (type_ == REMOTE)
    return;
  OpenDevTools(nullptr);
  scoped_refptr<content::DevToolsAgentHost> agent(
    content::DevToolsAgentHost::GetOrCreateFor(web_contents()));
  agent->InspectElement(x, y);
}
void WebContents::InspectServiceWorker() {
  if (type_ == REMOTE)
    return;
  for (const auto& agent_host : content::DevToolsAgentHost::GetOrCreateAll()) {
    if (agent_host->GetType() ==
        content::DevToolsAgentHost::TYPE_SERVICE_WORKER) {
      OpenDevTools(nullptr);
      managed_web_contents()->AttachTo(agent_host);
      break;
    }
  }
}
void WebContents::HasServiceWorker(