It would be a pretty good idea, if this was a chrome extension. However with .NET, if your building your own browser, it would be vulnerable to security threats (since the default is IE) which again is less portable compared to a chrome extension that can wrong in lots of Desktop OS.

Everyone is forgetting that the source also needs to be made public, and free for individual compiling, since a .NET app with administrative access is as powerful as any Trojan horse.