So few quick things, the projects that are copied are done so to guarantee deterministic builds in an isolated build environment (no dependencies on third party systems).
Yeah. Four commands. The first one downloads binaries from the internet. If I was inclined to do so, I would not need to build in the first place ;).
Give it a try with the current HEAD of their home-grown and undocumented build tool and see how far you get.
And regarding the deterministic builds: I call bullshit. They just don't want to follow the different packaging guidelines from the different operating systems, so they repackage everything. Now I have to trust them to keep all these dependencies up-to-date and I have to accept the unecessary bloat? No way.
That has nothing to do with their dependency management. In fact, if you link against system libraries, it should be simpler to get deterministic builds, as you have to build less.
So few quick things, the projects that are copied are done so to guarantee deterministic builds in an isolated build environment (no dependencies on third party systems).
The API you say they don't provide is literally the API that Electron uses. --> https://chromium.googlesource.com/chromium/src/+/HEAD/conten...
And as for the build process, eh, it's kinda slow but it's hardly arcane. On linux you can run like 4 commands and it'll build Chromeium.