window.botguard on google.com could very well be a way to detect bots running WebDriver to impersonate humans. Since WebDriver is headless, there would be detectable differences in WebGL support. This would also explain why the code is "very obfuscated".
That's exactly what it is. BotGuard isn't designed for identifying individual users, that's what cookies are for. It's designed to detect programs that are pretending to be normal web browsers being used but which aren't (because they're scripts, or rendering engines being automated, etc).
