Switching off Chrome is like "voting with your wallet", because you're increasing the market share of another entity / project, increasing its legitimacy in the eyes of your friends and colleagues or in the stats that all major websites are collecting on browsers.
But switching to Chromium does none of that.
Also stripping Google's integration out of Chromium leaves you with a much less capable browser. Are you, for example, willing to use Chromium without Google's Chrome Web Store?
I don't think so. But say that you're willing to keep using Google's Chrome Web Store, Chromium is open source, but the Chrome Web Store is not and all those extensions, reviews and users can't be moved, so what will happen if Google decides to disallow access to its store to Chromium users?
If you think that can't happen, consider that they did it for AOSP Android and that alternatives to Google Play might as well not exist ;-)
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If you're worried about Google's control of Chrome, switching to Chromium does nothing useful, the project is still under Google's control, you're still depending on their good will and you're doing nothing to diminish Chrome's dominance of the market.
Google has let the AOSP apps languish, and has used GApps as a bludgeon to keep control of the parts of Android they care about. Having phones running secure kernel versions obviously isn't a priority for Google, nor is consistent, functional E911 (look at the VoLTE shenanigans with Motorola and T-Mobile!).
What is a priority is building and extending the moat of GApps, locking services into relying on Maps APIs, push notifications, Play Games APIs, etc. Replacing these APIs is a huge task, and many apps will just outright crash if Google Maps isn't on your phone, let alone Google Play Services. The only reprieve is to use F-Droid, which is not the most consistently maintained app store.
Maybe my needs are much more modest than that of the average user, but, as a matter of fact, I do get by without using extensions from the Google Chrome store which are not open source. I do install open source ones from there, but I'm ready to download from source and avoid the store, which I do indeed do in some cases.
Even if Chromium's source is developed by Google employees, it being open source at least allows it to undergo scrutiny with respect to end-user-unfriendly behaviour.
But switching to Chromium does none of that.
Also stripping Google's integration out of Chromium leaves you with a much less capable browser. Are you, for example, willing to use Chromium without Google's Chrome Web Store?
I don't think so. But say that you're willing to keep using Google's Chrome Web Store, Chromium is open source, but the Chrome Web Store is not and all those extensions, reviews and users can't be moved, so what will happen if Google decides to disallow access to its store to Chromium users?
If you think that can't happen, consider that they did it for AOSP Android and that alternatives to Google Play might as well not exist ;-)
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If you're worried about Google's control of Chrome, switching to Chromium does nothing useful, the project is still under Google's control, you're still depending on their good will and you're doing nothing to diminish Chrome's dominance of the market.