src/vs/base/parts/ipc/electron-main/ipcMain.ts/ValidatedIpcMain/on
class ValidatedIpcMain:	on(channel: string, listener: ipcMainListener): this {

		// Remember the wrapped listener so that later we can
		// properly implement `removeListener`.
		const wrappedListener = (event: IpcMainEvent, ...args: any[]) => {
			if (this.validateEvent(channel, event)) {
				listener(event, ...args);
			}
		};

		this.mapListenerToWrapper.set(listener, wrappedListener);

		unsafeIpcMain.on(channel, wrappedListener);

		return this;
	}