Add support for checkbox with dialog.showMessageBox

This adds the `checkboxLabel` and `checkboxChecked` options to display a
checkbox in the message box. Fixes #6048.

lib/browser/api/dialog.js

@@ -178,7 +178,10 @@ module.exports = {
       }
     }
 
-    let {buttons, cancelId, defaultId, detail, icon, message, title, type} = options
+    let {
+      buttons, cancelId, checkboxLabel, checkboxChecked, defaultId, detail,
+      icon, message, title, type
+    } = options
 
     if (type == null) {
       type = 'none'
@@ -217,6 +220,14 @@ module.exports = {
       throw new TypeError('Detail must be a string')
     }
 
+    checkboxChecked = !!checkboxChecked
+
+    if (checkboxLabel == null) {
+      checkboxLabel = ''
+    } else if (typeof checkboxLabel !== 'string') {
+      throw new TypeError('checkboxLabel must be a string')
+    }
+
     if (icon == null) {
       icon = null
     }
@@ -239,8 +250,8 @@ module.exports = {
 
     const flags = options.noLink ? messageBoxOptions.noLink : 0
     return binding.showMessageBox(messageBoxType, buttons, defaultId, cancelId,
-                                  flags, title, message, detail, icon, window,
-                                  callback)
+                                  flags, title, message, detail, checkboxLabel,
+                                  checkboxChecked, icon, window, callback)
   },
 
   showErrorBox: function (...args) {