Add zoom menu item roles

lib/browser/api/menu-item-roles.js

@@ -72,6 +72,13 @@ const roles = {
     accelerator: 'Shift+CommandOrControl+Z',
     webContentsMethod: 'redo'
   },
+  resetzoom: {
+    label: 'Actual Size',
+    accelerator: 'CommandOrControl+0',
+    webContentsMethod: (webContents) => {
+      webContents.setZoomLevel(0)
+    }
+  },
   selectall: {
     label: 'Select All',
     accelerator: 'CommandOrControl+A',
@@ -106,9 +113,34 @@ const roles = {
   },
   zoom: {
     label: 'Zoom'
+  },
+  zoomin: {
+    label: 'Zoom In',
+    accelerator: 'CommandOrControl+Plus',
+    webContentsMethod: (webContents) => {
+      webContents.getZoomLevel((zoomLevel) => {
+        webContents.setZoomLevel(zoomLevel + 0.5)
+      })
+    }
+  },
+  zoomout: {
+    label: 'Zoom Out',
+    accelerator: 'CommandOrControl+-',
+    webContentsMethod: (webContents) => {
+      webContents.getZoomLevel((zoomLevel) => {
+        webContents.setZoomLevel(zoomLevel - 0.5)
+      })
+    }
   }
 }
 
+const canExecuteRole = (role) => {
+  if (!roles.hasOwnProperty(role)) return false
+  if (process.platform !== 'darwin') return true
+  // macOS handles all roles natively except the ones listed below
+  return ['zoomin', 'zoomout', 'resetzoom'].includes(role)
+}
+
 exports.getDefaultLabel = (role) => {
   if (roles.hasOwnProperty(role)) {
     return roles[role].label
@@ -122,8 +154,7 @@ exports.getDefaultAccelerator = (role) => {
 }
 
 exports.execute = (role, focusedWindow, focusedWebContents) => {
-  if (!roles.hasOwnProperty(role)) return false
-  if (process.platform === 'darwin') return false
+  if (!canExecuteRole(role)) return false
 
   const {appMethod, webContentsMethod, windowMethod} = roles[role]
 
@@ -142,7 +173,11 @@ exports.execute = (role, focusedWindow, focusedWebContents) => {
   }
 
   if (webContentsMethod && focusedWebContents != null) {
-    focusedWebContents[webContentsMethod]()
+    if (typeof webContentsMethod === 'function') {
+      webContentsMethod(focusedWebContents)
+    } else {
+      focusedWebContents[webContentsMethod]()
+    }
     return true
   }