src/vs/workbench/services/themes/browser/fileIconThemeData.ts/FileIconThemeLoader/load
class FileIconThemeLoader:	public load(data: FileIconThemeData): Promise<string | undefined> {
		if (!data.location) {
			return Promise.resolve(data.styleSheetContent);
		}
		return this.loadIconThemeDocument(data.location).then(iconThemeDocument => {
			const result = this.processIconThemeDocument(data.id, data.location!, iconThemeDocument);
			data.styleSheetContent = result.content;
			data.hasFileIcons = result.hasFileIcons;
			data.hasFolderIcons = result.hasFolderIcons;
			data.hidesExplorerArrows = result.hidesExplorerArrows;
			data.isLoaded = true;
			return data.styleSheetContent;
		});
	}