The rendering engine: Chromium had to be kept "libre", because khtml/Webkit was LGPL.
The browser: Chrome. could be kept closed because the LGPL allow the integration of libre libraries in closed products as long as the library itself remains "libre". In this case the library is the renering engine: Chromium.
As a counter example MacOS was built on top of decades of work on the BSD operating system and Apple is under no obligation to give the code back to the BSD project... and it doesn't.
So the most valuable company in the planet took from the community and it doesn't bother to give back.
Both companies did the bare minimum demanded by the respective license, its just that one license forces a bit more as bare minimum. Think. What does this mean?
If you use a license that demands even more, you could have pressurized the companies to behave even nicer.
Which would raise the bar for them requiring them to spend efforts writing it in house or procuring similar elsewhere. The more polished and complex a package is that is hard to find alternatives for, the better the leverage.
Yes, forced to follow. Its a sign in retrospect that KDE should have used an even stronger license. I don't know if AGPL existed then, but if I start a browser today, I'd license it as AGPL. If you want to use the project, you have to release your changes to your users. If you don't want to do that, good luck, spend millions on developing an equivalent application in house. Thats the beauty of GPL like licenses.
With BSD companies are under no obligation to release their changes, and like any self interested party, most don't.
The parent said GPL, which is what got me confused. LGPL makes more sense.
Although... this still doesn't explain why the other parts of the browser besides the rendering engine are open source? i.e. if the license was the reason, then presumably Google would've made the rest of the browser closed source, but that wasn't the case for most parts.
The browser: Chrome. could be kept closed because the LGPL allow the integration of libre libraries in closed products as long as the library itself remains "libre". In this case the library is the renering engine: Chromium.
As a counter example MacOS was built on top of decades of work on the BSD operating system and Apple is under no obligation to give the code back to the BSD project... and it doesn't.
So the most valuable company in the planet took from the community and it doesn't bother to give back.
For some of us that is unacceptabme.