Make the GN use_glib argument not user-selectable.

build/config/ui.gni

Index: build/config/ui.gni
diff --git a/build/config/ui.gni b/build/config/ui.gni
index bee5f484f54c23d02439d94e30fcbe3b3fa70b80..7d3c1693217db6c31e07cb59ebc5b8932014be2b 100644
--- a/build/config/ui.gni
+++ b/build/config/ui.gni
@@ -35,23 +35,12 @@ declare_args() {
 
   # Whether the entire browser uses toolkit-views on Mac instead of Cocoa.
   mac_views_browser = false
-
-  # Whether we should use glib, a low level C utility library.
-  use_glib = is_linux && !use_ozone
 }
 
 # Additional dependent variables -----------------------------------------------
 #
 # These variables depend on other variables and can't be set externally.
 
-if (is_linux && use_glib) {
-  use_cairo = true
-  use_pango = true
-} else {
-  use_cairo = false
-  use_pango = false
-}
-
 # Use GPU accelerated cross process image transport by default on linux builds
 # with the Aura window manager.
 ui_compositor_image_transport = use_aura && is_linux
@@ -61,6 +50,17 @@ use_default_render_theme = use_aura && !is_android
 # Indicates if the UI toolkit depends on X11.
 use_x11 = is_linux && !use_ozone
 
+# Whether we should use glib, a low level C utility library.
+use_glib = is_linux && !use_ozone
+
+if (is_linux && use_glib) {
+  use_cairo = true
+  use_pango = true
+} else {
+  use_cairo = false
+  use_pango = false
+}
+
 use_ozone_evdev = use_ozone
 
 use_clipboard_aurax11 = is_linux && use_aura && use_x11