Those are good examples. It was an honest question though, not a proclamation that Apple hasn't open sourced anything.
Edit: Maybe Google is getting more credit because of uptake? Chromium, golang, protobufs, material design, etc. So perhaps not how much was open source, but how much of it ended up in non Google projects?
Chromium was a fairly recent fork of WebKit. Webkit was already being adopted by every browser vendor except MS and Mozilla.
As far as Golang, I doubt that it has the uptake ofClang (even used by MS), CUPS, or Bonjour.
Yes I realized that CUPS was open source before being acquired by Apple but the copyright was owned by Sweets and they could have closed all future enhancement over the last decade.
You're talking about Blink. Chromium is not a rendering engine, but a full browser. Chrome is just chromium with branded assets and a few proprietary features that link it to Google Services.
It was first released in 2008, only 3 years after WebKit was open sourced, and about the same it was starting to gain traction outside Apple. Most of the browsers which didn't have their own engine back then were actually using Gecko or embedding an IE webview. Google embracing WebKit was a huge factor in pushing it to become the mainstream rendering engine.
Edit: Maybe Google is getting more credit because of uptake? Chromium, golang, protobufs, material design, etc. So perhaps not how much was open source, but how much of it ended up in non Google projects?