I’m using piwik on few sites and it works fine. The only issue I have is failed status in Chromium developer tools. It looks the same regardles I’m using default javascript code from piwik administration panel or asynchronous method (even when I look at piwik.org I have this strange error).
Javascript console shows (this anonymous functions are propably result of how asynchronous method work):
GET http://p.site.com/piwik.js site.com:119
(anonymous function) site.com:119
(anonymous function) site.com:119
Strange thing is that piwik statistics are working fine and until now I don’t see need to fix this. But until upgrade to 1.10.1 I really want overlay feature and I’m still getting error:
The Page Overlay session couldn't be launched yet.
Maybe the page loaded on the right doesn't have the Piwik tracker code. In this case, try launching Overlay for a different page from the pages report.
I’ve tried sugested tips but without success 
Now I’m asking for your help to solve my issue - please ask if you need more detailed info.