chromium: fix GL support by not using the ANGLE GL implementation

pkgs/applications/networking/browsers/chromium/common.nix

@@ -137,6 +137,7 @@ let
       ./patches/remove-webp-include-69.patch
       ./patches/no-build-timestamps.patch
       ./patches/widevine-79.patch
+      ./patches/dont-use-ANGLE-by-default.patch
       # Unfortunately, chromium regularly breaks on major updates and
       # then needs various patches backported in order to be compiled with GCC.
       # Good sources for such patches and other hints:

pkgs/applications/networking/browsers/chromium/patches/dont-use-ANGLE-by-default.patch

@@ -0,0 +1,26 @@
+A field trial currently enables the passthrough command decoder, which causes
+gl_factory.cc to try kGLImplementationEGLANGLE first, which causes Chromium to fail
+to load libGLESv2.so on NixOS.  It somehow does not try kGLImplementationDesktopGL,
+and so there is no GL support at all.
+
+Revert to using the validating command decoder, which prevents gl_factory.cc
+from touching allowed_impls, allowing it to successfully use kGLImplementationDesktopGL.
+
+diff --git a/ui/gl/gl_utils.cc b/ui/gl/gl_utils.cc
+index 697cbed5fe2d..8419bdb21a2f 100644
+--- a/ui/gl/gl_utils.cc
++++ b/ui/gl/gl_utils.cc
+@@ -71,9 +71,10 @@ bool UsePassthroughCommandDecoder(const base::CommandLine* command_line) {
+   } else if (switch_value == kCmdDecoderValidatingName) {
+     return false;
+   } else {
+-    // Unrecognized or missing switch, use the default.
+-    return base::FeatureList::IsEnabled(
+-        features::kDefaultPassthroughCommandDecoder);
++    // Ignore the field trial that enables it; disable it until
++    // gl_factory.cc kGLImplementationEGLANGLE issues are sorted
++    // out on NixOS.
++    return false;
+   }
+ }
+ }