• Electron version: 1.8.0 beta
• Operating system: macOS 10.12.6

Expected behavior

Browser window's vibrancy settings persists after closing detached devtools

Actual behavior

Closing detached devtools will disable browser window's vibrancy, and calling setVibrancy again can't re-enable it.

How to reproduce

The repo for reproducing is https://github.com/KagamiChan/electron-quick-start in branch 1.8.0-vibrancy-mac. I simply added these lines in renderer.js

const { remote } = require('electron')

const win = remote.getCurrentWindow()
win.setVibrancy('ultra-dark')

win.webContents.openDevTools({mode: 'detach'})

win.webContents.on('devtools-closed', () => {
  setTimeout(() => {
    console.log('restoring vibrancy')
    win.setVibrancy('ultra-dark')
  }, 1000)
})

Steps to reproduce:

1. git clone -b 1.8.0-vibrancy-mac https://github.com/KagamiChan/electron-quick-start
2. cd electron-quick-start && npm i && npm run start
3. Close the detached devtools
4. the browser window loses vibrancy

btw, In previous version (1.7.5), non-detached devtools breaks the vibrancy but then it will restore after closing the devtools, and in 1.8.0 the vibrancy does not come back either.