No sources_assignment_filter

There is a strong consensus that the set_sources_assignment_filter feature from GN is a mis-feature and should be removed. This requires that Chromium's BUILD.gn file stop using the feature.

Since October 2020, the filter is no longer used.

Chromium build does not set a default sources assignment filter, and all build files must manage sources with explicit if statements.

Explicit assignment

If you have a target that have platform specific implementation files, you can use the following pattern:

  source_set("foo") {
    sources = [
      "foo.h",
    ]
    if (is_mac) {
      sources += [
        "foo_mac.mm",
      ]
    }
    if (is_win) {
      sources += [
        "foo_win.cc",
      ]
    }
    if (is_linux) {
      sources += [
        "foo_linux.cc",
      ]
    }
  }