src/vs/workbench/browser/parts/editor/editorPane.ts/EditorMemento/saveState
class EditorMemento:	saveState(): void {
		const cache = this.doLoad();

		// Cleanup once during session
		if (!this.cleanedUp) {
			this.cleanUp();
			this.cleanedUp = true;
		}

		this.memento[this.key] = cache.toJSON();
	}