yeah. Inotify and such. I believe that sort of thing is what they Zygote process for (as mentioned in the blog post), which is extra steps that they don't have to do on other systems.
The code used to do such things is suppose to be rather ugly, but unfortunately Google has terminated it's code search stuff and thus the links from his post showing what Chrome does is broken. I don't have time to hunt down the details myself right now.