Yea. It's not just the add-ons, data collection has always been a major concern about Google Chrome.
There has always been this notion that Firefox does not collect as much personal data as Google Chrome.
Could you post more on how Chromium is diffefent in that regard?
I am not sure which regard you are referring to, but here is my response to what I am guessing you want to know:
First some notes: I have not tested newer Firefox version series than the 24 series. My own use Google Chrome is limited to earlier version(s), but after the inclusion of Chrome Frame. I had used some versions of Chromium, particularity near the end of support for Chromium Frame.
Up through Firefox 24 series, The Firefox browser (which is open-source) may collect client data that may be helpful for its browser development. This may include some client information, but the information may be important for the development purpose (such as the URL of a page that resulted in the crashing of the browser). The various data collection features are optional and may be disabled (and some by default in various versions).
In contrast, Google Chrome collects much more, seemingly, for Google's own, non-browser purposes. Also, although not Google Chrome necessarily itself, the installer and and the bundled software install the software in a manner expected of malware. After my tests, I had rejected Google Chrome due to my general policy against malware and also due to its rather lacking User Interface and printing support.
Chromium, lacks the closed-source monitoring "features" of Google Chrome. On its surface, it does appear to be so geared to necessarily to make information available to Google; there are options to send Google information to Google (I forgot what information) and references to "Google Chrome" within it (but are not visible by default). Though I sometimes retain a copy of some (now older) versions of Chromium on some systems, I typically do not use use or recommend it due to its lacking User Interface and printing features.
