src/vs/workbench/services/history/browser/history.ts/HistoryService/saveState
class HistoryService:	private saveState(): void {
		if (!this.history) {
			return; // nothing to save because history was not used
		}

		const entries: ISerializedEditorHistoryEntry[] = [];
		for (const editor of this.history) {
			if (editor instanceof EditorInput || !isResourceEditorInput(editor)) {
				continue; // only save resource editor inputs
			}

			entries.push({ editor });
		}

		this.storageService.store(HistoryService.HISTORY_STORAGE_KEY, stringify(entries), StorageScope.WORKSPACE, StorageTarget.MACHINE);
	}