src/vs/workbench/contrib/update/browser/update.ts/UpdateContribution/shouldShowNotification
class UpdateContribution:	private shouldShowNotification(): boolean {
		const currentVersion = this.productService.commit;
		const currentMillis = new Date().getTime();
		const lastKnownVersion = this.storageService.get('update/lastKnownVersion', StorageScope.APPLICATION);

		// if version != stored version, save version and date
		if (currentVersion !== lastKnownVersion) {
			this.storageService.store('update/lastKnownVersion', currentVersion!, StorageScope.APPLICATION, StorageTarget.MACHINE);
			this.storageService.store('update/updateNotificationTime', currentMillis, StorageScope.APPLICATION, StorageTarget.MACHINE);
		}

		const updateNotificationMillis = this.storageService.getNumber('update/updateNotificationTime', StorageScope.APPLICATION, currentMillis);
		const diffDays = (currentMillis - updateNotificationMillis) / (1000 * 60 * 60 * 24);

		return diffDays > 5;
	}