src/vs/workbench/common/memento.ts/Memento/clear
class Memento:	static clear(scope: StorageScope): void {
		switch (scope) {
			case StorageScope.WORKSPACE:
				Memento.workspaceMementos.clear();
				break;
			case StorageScope.PROFILE:
				Memento.profileMementos.clear();
				break;
			case StorageScope.APPLICATION:
				Memento.applicationMementos.clear();
				break;
		}
	}