refactor: convert more files to typescript (#16820)

lib/browser/api/protocol.ts

@@ -0,0 +1,29 @@
+import { app, session } from 'electron'
+
+// Global protocol APIs.
+const protocol = process.atomBinding('protocol')
+
+// Fallback protocol APIs of default session.
+Object.setPrototypeOf(protocol, new Proxy({}, {
+  get (target, property) {
+    if (!app.isReady()) return
+
+    const protocol = session.defaultSession!.protocol
+    if (!Object.getPrototypeOf(protocol).hasOwnProperty(property)) return
+
+    // Returning a native function directly would throw error.
+    return (...args: any[]) => (protocol[property as keyof Electron.Protocol] as Function)(...args)
+  },
+
+  ownKeys () {
+    if (!app.isReady()) return []
+
+    return Object.getOwnPropertyNames(Object.getPrototypeOf(session.defaultSession!.protocol))
+  },
+
+  getOwnPropertyDescriptor (target) {
+    return { configurable: true, enumerable: true }
+  }
+}))
+
+export default protocol