src/vs/code/browser/workbench/workbench.ts/PollingURLCallbackProvider/periodicFetchCallback
class PollingURLCallbackProvider:	private async periodicFetchCallback(requestId: string, startTime: number): Promise<void> {

		// Ask server for callback results
		const queryValues: Map<string, string> = new Map();
		queryValues.set(PollingURLCallbackProvider.QUERY_KEYS.REQUEST_ID, requestId);

		const result = await request({
			url: doCreateUri('/fetch-callback', queryValues).toString(true)
		}, CancellationToken.None);

		// Check for callback results
		const content = await streamToBuffer(result.stream);
		if (content.byteLength > 0) {
			try {
				this._onCallback.fire(URI.revive(JSON.parse(content.toString())));
			} catch (error) {
				console.error(error);
			}

			return; // done
		}

		// Continue fetching unless we hit the timeout
		if (Date.now() - startTime < PollingURLCallbackProvider.FETCH_TIMEOUT) {
			setTimeout(() => this.periodicFetchCallback(requestId, startTime), PollingURLCallbackProvider.FETCH_INTERVAL);
		}
	}