src/vs/workbench/services/history/browser/history.ts/HistoryService/clear
class HistoryService:	clear(): void {

		// History
		this.clearRecentlyOpened();

		// Navigation (next, previous)
		this.navigationStackIndex = -1;
		this.lastNavigationStackIndex = -1;
		this.navigationStack.splice(0);
		this.editorStackListeners.forEach(listeners => dispose(listeners));
		this.editorStackListeners.clear();

		// Recently closed editors
		this.recentlyClosedEditors = [];

		// Context Keys
		this.updateContextKeys();
	}