More build config cleanup.

build/config/ui.gni

Index: build/config/ui.gni
diff --git a/build/config/ui.gni b/build/config/ui.gni
index 90f8b86c865c6413275e527aea8b340c6a853891..1d0a3f092af35d40e50b783a1b0abab26e3b1a71 100644
--- a/build/config/ui.gni
+++ b/build/config/ui.gni
@@ -12,17 +12,10 @@
 # See also build/config/features.gni
 
 declare_args() {
-  # Indicates if Ash is enabled. Ash is the Aura Shell which provides a
-  # desktop-like environment for Aura. Requires use_aura = true
-  use_ash = is_linux
-
   # Indicates if Ozone is enabled. Ozone is a low-level library layer for Linux
   # that does not require X11.
   use_ozone = false
 
-  # Support ChromeOS touchpad gestures with ozone.
-  use_evdev_gestures = false
-
   # Indicates if Aura is enabled. Aura is a low-level windowing library, sort
   # of a replacement for GDI or GTK.
   use_aura = is_linux
@@ -32,10 +25,6 @@ declare_args() {
 #
 # These variables depend on other variables and can't be set externally.
 
-# TODO(vtl): Probably should get rid of these variables.
-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