I'm about to switch to Chromium and I installed a couple of extensions. Each time I installed an extension I was notified of which data the extension has access to, e.g.:
I do understand that access to that data is necessary for the extension to work, yet I'm a bit worried that such an extension might one day decide to update and steal ("phone home") all my browsing data.
Another example of a scary message (when enabling extensions for incognito windows):
Warning: Chromium cannot prevent extensions from recording your browsing history. To disable this extension in incognito mode, unselect this option.
Is that a possible threat when using popular Chrome extensions? It's a bit scary to have to trust another party for each new function you add to the browser.
Best Answer
You are forgetting the following:
The more popular an extension is, the smaller is the chance of nobody noticing that the add-on does something harmful.
In contrast to that, if you install some extension that nobody else has used before, you risk more than, let's say, installing AdBlock. Considering that so many people are using it, it is almost safe to say: Someone would have noticed unusual traffic.
In fact, all extensions disclose their source code, so anybody could basically go ahead and look for anything suspicious themselves.
The warnings are just there so you can't blame the browser vendors for any damage done, in case you install something that goes rogue with your data. Always read the reviews of add-ons that look suspect to you before installing them.
Also note that, for example Google can check the submissions:
Removal of an extension can of course cause some trouble to the developer.