refactor: allow requiring modules with no side effects (#17496)

lib/browser/api/power-monitor.ts

@@ -0,0 +1,48 @@
+'use strict'
+
+import { createLazyInstance } from '../utils'
+
+const { EventEmitter } = require('events')
+const { createPowerMonitor, PowerMonitor } = process.electronBinding('power_monitor')
+const { deprecate } = require('electron')
+
+// PowerMonitor is an EventEmitter.
+Object.setPrototypeOf(PowerMonitor.prototype, EventEmitter.prototype)
+
+const powerMonitor = createLazyInstance(createPowerMonitor, PowerMonitor, true)
+
+// On Linux we need to call blockShutdown() to subscribe to shutdown event.
+if (process.platform === 'linux') {
+  powerMonitor.on('newListener', (event:string) => {
+    if (event === 'shutdown' && powerMonitor.listenerCount('shutdown') === 0) {
+      powerMonitor.blockShutdown()
+    }
+  })
+
+  powerMonitor.on('removeListener', (event: string) => {
+    if (event === 'shutdown' && powerMonitor.listenerCount('shutdown') === 0) {
+      powerMonitor.unblockShutdown()
+    }
+  })
+}
+
+// TODO(nitsakh): Remove in 7.0
+powerMonitor.querySystemIdleState = function (threshold: number, callback: Function) {
+  deprecate.warn('powerMonitor.querySystemIdleState', 'powerMonitor.getSystemIdleState')
+  if (typeof threshold !== 'number') throw new Error('Must pass threshold as a number')
+  if (typeof callback !== 'function') throw new Error('Must pass callback as a function argument')
+
+  const idleState = this.getSystemIdleState(threshold)
+  process.nextTick(() => callback(idleState))
+}
+
+// TODO(nitsakh): Remove in 7.0
+powerMonitor.querySystemIdleTime = function (callback: Function) {
+  deprecate.warn('powerMonitor.querySystemIdleTime', 'powerMonitor.getSystemIdleTime')
+  if (typeof callback !== 'function') throw new Error('Must pass function as an argument')
+
+  const idleTime = this.getSystemIdleTime()
+  process.nextTick(() => callback(idleTime))
+}
+
+module.exports = powerMonitor