The official Chrome extensions documentation seems terribly out of date. For example, this page references chrome.tabs.getSelected() method, which has been deprecated long ago (one should use chrome.tabs.query() now).
The samples page is also outdated. Almost none of the samples I checked worked.
So, naturally, I wonder, when can one get relevant documentation on Google Chrome extensions?
The API documentation should be current. If you want something more tutorial-like the other pages are useful but you should cross-check with the API reference since you are correct that the APIs still change relatively often.