Fix ash 'gn check' errors; whitelist target.

.gn

 # This file is used by the GN meta build system to find the root of the source
 # tree and to set startup options. For documentation on the values set in this
 # file, run "gn help dotfile" at the command line.
 
 # The location of the build configuration file.
 buildconfig = "//build/config/BUILDCONFIG.gn"
 
 # The secondary source root is a parallel directory tree where
 # GN build files are placed when they can not be placed directly
 # in the source tree, e.g. for third party source trees.
 secondary_source = "//build/secondary/"
 
 # These are the targets to check headers for by default. The files in targets
 # matching these patterns (see "gn help label_pattern" for format) will have
 # their includes checked for proper dependencies when you run either
 # "gn check" or "gn gen --check".
 check_targets = [
   #"//apps/*",  # Medium-hard.
-  #"//ash/*",  # Medium-hard.
+  "//ash/*",
   "//base/*",
   "//blink/*",
   "//breakpad/*",
   "//build/*",
   "//cc/*",
 
   #"//chrome/*",  # Epic number of errors.
   "//chrome/app/*",
   "//chrome/common/*",
   "//chrome/installer/*",
@@ skipping 200 matching lines @@
   "//tools/gn/format_test_data/055.golden",
   "//tools/gn/function_exec_script.cc",
   "//tools/gn/gn.gyp",
   "//tools/gn/input_conversion.cc",
   "//tools/gn/misc/emacs/gn.el",
   "//tools/gn/misc/vim/syntax/gn.vim",
   "//tools/gn/setup.cc",
   "//ui/accessibility/BUILD.gn",
   "//ui/views/BUILD.gn",
 ]