src/vs/workbench/api/browser/mainThreadDocuments.ts/MainThreadDocuments/_onModelModeChanged
class MainThreadDocuments:	private _onModelModeChanged(event: { model: ITextModel; oldLanguageId: string }): void {
		const { model } = event;
		if (!this._modelTrackers.has(model.uri)) {
			return;
		}
		this._proxy.$acceptModelLanguageChanged(model.uri, model.getLanguageId());
	}