refactor: ginify powerMonitor (#22751)

lib/browser/api/power-monitor.ts

@@ -1,38 +1,46 @@
-'use strict';
+import { EventEmitter } from 'events';
+import { app } from 'electron';
 
-import { createLazyInstance } from '../utils';
+const { createPowerMonitor, getSystemIdleState, getSystemIdleTime } = process.electronBinding('power_monitor');
 
-const { EventEmitter } = require('events');
-const { createPowerMonitor, PowerMonitor } = process.electronBinding('power_monitor');
+class PowerMonitor extends EventEmitter {
+  constructor () {
+    super();
+    // Don't start the event source until both a) the app is ready and b)
+    // there's a listener registered for a powerMonitor event.
+    this.once('newListener', () => {
+      app.whenReady().then(() => {
+        const pm = createPowerMonitor();
+        pm.emit = this.emit.bind(this);
 
-// PowerMonitor is an EventEmitter.
-Object.setPrototypeOf(PowerMonitor.prototype, EventEmitter.prototype);
-
-const powerMonitor = createLazyInstance(createPowerMonitor, PowerMonitor, true);
-
-if (process.platform === 'linux') {
-  // In order to delay system shutdown when e.preventDefault() is invoked
-  // on a powerMonitor 'shutdown' event, we need an org.freedesktop.login1
-  // shutdown delay lock. For more details see the "Taking Delay Locks"
-  // section of https://www.freedesktop.org/wiki/Software/systemd/inhibit/
-  //
-  // So here we watch for 'shutdown' listeners to be added or removed and
-  // set or unset our shutdown delay lock accordingly.
-  const { app } = require('electron');
-  app.whenReady().then(() => {
-    powerMonitor.on('newListener', (event: string) => {
-      // whenever the listener count is incremented to one...
-      if (event === 'shutdown' && powerMonitor.listenerCount('shutdown') === 0) {
-        powerMonitor.blockShutdown();
-      }
+        if (process.platform === 'linux') {
+          // On Linux, we inhibit shutdown in order to give the app a chance to
+          // decide whether or not it wants to prevent the shutdown. We don't
+          // inhibit the shutdown event unless there's a listener for it. This
+          // keeps the C++ code informed about whether there are any listeners.
+          pm.setListeningForShutdown(this.listenerCount('shutdown') > 0);
+          this.on('newListener', (event) => {
+            if (event === 'shutdown') {
+              pm.setListeningForShutdown(this.listenerCount('shutdown') + 1 > 0);
+            }
+          });
+          this.on('removeListener', (event) => {
+            if (event === 'shutdown') {
+              pm.setListeningForShutdown(this.listenerCount('shutdown') > 0);
+            }
+          });
+        }
+      });
     });
-    powerMonitor.on('removeListener', (event: string) => {
-      // whenever the listener count is decremented to zero...
-      if (event === 'shutdown' && powerMonitor.listenerCount('shutdown') === 0) {
-        powerMonitor.unblockShutdown();
-      }
-    });
-  });
+  }
+
+  getSystemIdleState (idleThreshold: number) {
+    return getSystemIdleState(idleThreshold);
+  }
+
+  getSystemIdleTime () {
+    return getSystemIdleTime();
+  }
 }
 
-module.exports = powerMonitor;
+module.exports = new PowerMonitor();