As pointed out by @calavera.info, @iman.Bahrampour, and @Asim K T this feature is now available in Chrome 59. You can select a URL or domain to block in the Network panel. See this release note and these Screenshots where the StackOverflow logo has been blocked from this page. @iman.Bahrampour also shares two extensions below that will also do this (“HTTP Request Blocker” and “Request Blocker”).
