> In order to provide the smoothest experience as possible, the extension needs to know when you change active tabs. In order for the extension to know about that event, it needs the tabs permission, which Chrome describes as "can read and change all your data on websites you visit." That description is very scary, and is certainly not what this extension is doing. Being an open-sourced project, you can always read all the code to see how this extension works, and what it's [not] doing with your data.
The problem is that even if I read the code, or more likely chose to trust that someone has, it's not guaranteed to remain true for future updates. The author's scruples may weaken with time, or they might sell the extension, etc. (I think Chrome's extensions auto-update, but even if they didn't I'd still have to remember that this extension is one that I can't assume it's safe to update.)
The problem is that even if I read the code, or more likely chose to trust that someone has, it's not guaranteed to remain true for future updates. The author's scruples may weaken with time, or they might sell the extension, etc. (I think Chrome's extensions auto-update, but even if they didn't I'd still have to remember that this extension is one that I can't assume it's safe to update.)