Rename is_chromeos.

build/config/features.gni

Index: build/config/features.gni
diff --git a/build/config/features.gni b/build/config/features.gni
index b1e9280c0921a5e4d1057ed114f07f16961abc40..abd8b9a7b68eb6ed3ff21c8de75adfebda18018b 100644
--- a/build/config/features.gni
+++ b/build/config/features.gni
@@ -25,6 +25,11 @@ declare_args() {
 
   enable_plugins = !is_android && !is_ios
 
+  # This indicates whether the chromeos interfaces and features should be
+  # made available.  Contrast with whether we are targetting the embedded
+  # OS.  That flag controls the linking, flags, filesystems, etc. we expect.
+  use_cros_fe = is_chromeos
+
   # Enables Native Client support.
   # TODO(GYP): Get NaCl linking on other platforms.
   # Also, see if we can always get rid of enable_nacl_untrusted and
@@ -209,3 +214,18 @@ enable_pre_sync_backup = is_win || is_mac || (is_linux && !is_chromeos)
 
 # WebVR support disabled until platform implementations have been added
 enable_webvr = false
+
+#
+#  Maintain some sanity for refactoring build configs.
+#
+if (is_chromeos_os) {
+  assert(use_cros_fe, "ChromeOS targetting requires ChromeOS UI")
+}
+
+if (use_cros_fe) {
+  assert(!is_desktop_linux, "ChromeOS Frontend is not desktop linux")
+}
+
+assert(use_cros_fe == is_chromeos,
+       "is_chromeos and use_cros_fe are expected to be aliases, " +
+           "old and new, respectively")