src/vs/workbench/browser/parts/editor/editorsObserver.ts/EditorsObserver/loadState
class EditorsObserver:	private loadState(): void {
		const serialized = this.storageService.get(EditorsObserver.STORAGE_KEY, StorageScope.WORKSPACE);

		// Previous state: Load editors map from persisted state
		if (serialized) {
			this.deserialize(JSON.parse(serialized));
		}

		// No previous state: best we can do is add each editor
		// from oldest to most recently used editor group
		else {
			const groups = this.editorGroupsService.getGroups(GroupsOrder.MOST_RECENTLY_ACTIVE);
			for (let i = groups.length - 1; i >= 0; i--) {
				const group = groups[i];
				const groupEditorsMru = group.getEditors(EditorsOrder.MOST_RECENTLY_ACTIVE);
				for (let i = groupEditorsMru.length - 1; i >= 0; i--) {
					this.addMostRecentEditor(group, groupEditorsMru[i], true /* enforce as active to preserve order */, true /* is new */);
				}
			}
		}

		// Ensure we listen on group changes for those that exist on startup
		for (const group of this.editorGroupsService.groups) {
			this.registerGroupListeners(group);
		}
	}