src/vs/server/node/webClientServer.ts/WebClientServer/_handleCallback
class WebClientServer:	private async _handleCallback(res: http.ServerResponse): Promise<void> {
		const filePath = FileAccess.asFileUri('vs/code/browser/workbench/callback.html', require).fsPath;
		const data = (await util.promisify(fs.readFile)(filePath)).toString();
		const cspDirectives = [
			'default-src \'self\';',
			'img-src \'self\' https: data: blob:;',
			'media-src \'none\';',
			`script-src 'self' ${this._getScriptCspHashes(data).join(' ')};`,
			'style-src \'self\' \'unsafe-inline\';',
			'font-src \'self\' blob:;'
		].join(' ');

		res.writeHead(200, {
			'Content-Type': 'text/html',
			'Content-Security-Policy': cspDirectives
		});
		return res.end(data);
	}