Reduces the IPC messages used for visibilityState

lib/renderer/override.js

@@ -3,17 +3,6 @@
 const ipcRenderer = require('electron').ipcRenderer
 const remote = require('electron').remote
 
-// Cache browser window visibility
-var _isVisible = true
-var _isMinimized = false
-var initWindow = function initWindow () {
-  var currentWindow
-  currentWindow = remote.getCurrentWindow()
-  _isVisible = currentWindow.isVisible()
-  _isMinimized = currentWindow.isMinimized()
-}
-initWindow()
-
 // Helper function to resolve relative url.
 var a = window.top.document.createElement('a')
 
@@ -200,17 +189,6 @@ if (process.openerId != null) {
   window.opener = BrowserWindowProxy.getOrCreate(process.openerId)
 }
 
-ipcRenderer.on('ELECTRON_RENDERER_WINDOW_VISIBILITY_CHANGE', function (event, isVisible, isMinimized) {
-  var hasChanged = _isVisible !== isVisible || _isMinimized !== isMinimized
-
-  if (hasChanged) {
-    _isVisible = isVisible
-    _isMinimized = isMinimized
-
-    document.dispatchEvent(new Event('visibilitychange'))
-  }
-})
-
 ipcRenderer.on('ELECTRON_GUEST_WINDOW_POSTMESSAGE', function (event, sourceId, message, sourceOrigin) {
   // Manually dispatch event instead of using postMessage because we also need to
   // set event.source.
@@ -249,19 +227,24 @@ Object.defineProperty(window.history, 'length', {
   }
 })
 
+// Subscribe to visibilityState changes.
+let cachedVisibilityState = 'hidden'
+ipcRenderer.on('ELECTRON_RENDERER_WINDOW_VISIBILITY_CHANGE', function (event, visibilityState) {
+  if (cachedVisibilityState != visibilityState) {
+    cachedVisibilityState = visibilityState
+    document.dispatchEvent(new Event('visibilitychange'))
+  }
+})
+
 // Make document.hidden and document.visibilityState return the correct value.
 Object.defineProperty(document, 'hidden', {
   get: function () {
-    return _isMinimized || !_isVisible
+    return cachedVisibilityState != 'visible'
   }
 })
 
 Object.defineProperty(document, 'visibilityState', {
   get: function () {
-    if (_isVisible && !_isMinimized) {
-      return 'visible'
-    } else {
-      return 'hidden'
-    }
+    return cachedVisibilityState
   }
 })