src/vs/workbench/services/workingCopy/common/workingCopyBackupTracker.ts/WorkingCopyBackupTracker/onDidChangeDirty
class WorkingCopyBackupTracker:	private onDidChangeDirty(workingCopy: IWorkingCopy): void {
		if (workingCopy.isDirty()) {
			this.scheduleBackup(workingCopy);
		} else {
			this.discardBackup(workingCopy);
		}
	}