src/vs/workbench/contrib/themes/browser/themes.contribution.ts/MarketplaceThemesPicker/trigger
class MarketplaceThemesPicker:	public trigger(value: string) {
		if (this._tokenSource) {
			this._tokenSource.cancel();
			this._tokenSource = undefined;
		}
		this._queryDelayer.trigger(() => {
			this._tokenSource = new CancellationTokenSource();
			return this.doSearch(value, this._tokenSource.token);
		});
	}