src/vs/workbench/api/browser/mainThreadDocuments.ts/MainThreadDocuments/_onModelAdded
class MainThreadDocuments:	private _onModelAdded(model: ITextModel): void {
		// Same filter as in mainThreadEditorsTracker
		if (!shouldSynchronizeModel(model)) {
			// don't synchronize too large models
			return;
		}
		this._modelIsSynced.set(model.uri, undefined);
		this._modelTrackers.set(model.uri, new ModelTracker(model, this._onIsCaughtUpWithContentChanges, this._proxy, this._textFileService));
	}