Fix two typos in the documentation of some args of GN.

build/config/ui.gni

 # Copyright 2014 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
 # This file contains UI-related build flags. It should theoretically be in the
 # src/ui directory and only things that depend on the ui module should get the
 # definitions.
 #
 # However, today we have many "bad" dependencies on some of these flags from,
 # e.g. base, so they need to be global.
 #
 # See also build/config/features.gni
 
 declare_args() {
-  # Indicates if Ash is enabled. Ash is the Aura SHell which provides a
+  # 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_win || is_chromeos
 
   # Indicates if Ozone is enabled. Ozone is a low-level library layer for Linux
   # that does not require X11.
   use_ozone = 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 || use_ozone || is_win || is_chromeos || use_ash
 
   # XInput2 multitouch support. Zero means disabled, nonzero indicates the
   # minimum XI2 version. For example, use_xi2_mt=2 means XI2.2 or above.
   use_xi2_mt = 2
 
-  # True means the UI is built useing the "views" framework.
+  # True means the UI is built using the "views" framework.
   toolkit_views = is_win || is_chromeos || use_aura
 }
 
 # Additional dependent variables -----------------------------------------------
 #
 # These variables depend on other variables and can't be set externally.
 
 if (is_linux) {
   use_cairo = true
   use_pango = true
@@ skipping 12 matching lines @@
 use_default_render_theme = use_aura || is_linux
 
 # Indicates if the UI toolkit depends on X11.
 use_x11 = is_linux && !use_ozone
 
 use_glib = is_linux
 
 use_clipboard_aurax11 = is_linux && use_aura && use_x11
 
 ozone_platform_dri = use_ozone