src/vs/platform/contextkey/browser/contextKeyService.ts/ScopedContextKeyService/_updateParentChangeListener
class ScopedContextKeyService:	private _updateParentChangeListener(): void {
		// Forward parent events to this listener. Parent will change.
		this._parentChangeListener.value = this._parent.onDidChangeContext(this._onDidChangeContext.fire, this._onDidChangeContext);
	}