Remove Chrome OS-related GN build configuration

build/config/features.gni

Index: build/config/features.gni
diff --git a/build/config/features.gni b/build/config/features.gni
index d1bdfbca0dd381db64ee12ef4e241dff4553f04c..a235be4ac9ac996571e8b23343724fe364a0cf16 100644
--- a/build/config/features.gni
+++ b/build/config/features.gni
@@ -31,7 +31,7 @@ declare_args() {
   # the commented out logic.
   # Eventually we want this to be:
   #   enable_nacl = !is_ios && !is_android
-  enable_nacl = (is_linux && !is_chromeos && current_cpu == "x64") || is_nacl
+  enable_nacl = (is_linux && current_cpu == "x64") || is_nacl
   enable_nacl_untrusted = enable_nacl
   enable_pnacl = enable_nacl_untrusted
 }