Rename is_chromeos.

build/config/BUILDCONFIG.gn

Index: build/config/BUILDCONFIG.gn
diff --git a/build/config/BUILDCONFIG.gn b/build/config/BUILDCONFIG.gn
index c91db167b34dcc8adcd98dab2e09835599b89727..2fce0ad835f0237793dd2c130fd72a99f083731d 100644
--- a/build/config/BUILDCONFIG.gn
+++ b/build/config/BUILDCONFIG.gn
@@ -125,8 +125,14 @@ declare_args() {
   # Debug build.
   is_debug = true
 
+  # Whether we're building components and interfaces for ChromeOS
+  # This is for backwards compatability until the rename in complete in all
+  # dependent files.  See use_cros_fe in features.gni.  They should be the same.
+  # TODO(petermayo): Remove this when it doesn't break known compiles.
+  is_chromeos = current_os == "chromeos"
+
   # Whether we're a traditional desktop unix.
-  is_desktop_linux = current_os == "linux" && current_os != "chromeos"
+  is_desktop_linux = current_os == "linux" && !is_chromeos
 
   # Set to true when compiling with the Clang compiler. Typically this is used
   # to configure warnings.
@@ -150,6 +156,8 @@ declare_args() {
     # to support the CrOS build system which supports per-build-configuration
     # toolchains.
     cros_use_custom_toolchain = false
+  } else {
+    cros_use_custom_toolchain = false
   }
 
   # DON'T ADD MORE FLAGS HERE. Read the comment above.
@@ -162,12 +170,16 @@ declare_args() {
 # We set these various is_FOO booleans for convenience in writing OS-based
 # conditions.
 #
-# - is_android, is_chromeos, is_ios, and is_win should be obvious.
+# - is_android, is_ios, and is_win should be obvious.
 # - is_mac is set only for desktop Mac. It is not set on iOS.
 # - is_posix is true for mac and any Unix-like system (basically everything
 #   except Windows).
 # - is_linux is true for desktop Linux and ChromeOS, but not Android (which is
 #   generally too different despite being based on the Linux kernel).
+# - is_chromeos_os is true if the results are expected to run on a ChromeOS
+#   machine, using the filesystem and runtime libraries specifed by
+#   a build of that OS, rather than local linux.  E.g. presume an update
+#   system, journalled files system, storage modes, no other apps, etc.
 #
 # Do not add more is_* variants here for random lesser-used Unix systems like
 # aix or one of the BSDs. If you need to check these, just check the
@@ -176,7 +188,7 @@ declare_args() {
 if (current_os == "win" || current_os == "winrt_81" ||
     current_os == "winrt_81_phone" || current_os == "winrt_10") {
   is_android = false
-  is_chromeos = false
+  is_chromeos_os = false
   is_ios = false
   is_linux = false
   is_mac = false
@@ -185,7 +197,7 @@ if (current_os == "win" || current_os == "winrt_81" ||
   is_win = true
 } else if (current_os == "mac") {
   is_android = false
-  is_chromeos = false
+  is_chromeos_os = false
   is_ios = false
   is_linux = false
   is_mac = true
@@ -194,7 +206,7 @@ if (current_os == "win" || current_os == "winrt_81" ||
   is_win = false
 } else if (current_os == "android") {
   is_android = true
-  is_chromeos = false
+  is_chromeos_os = false
   is_ios = false
   is_linux = false
   is_mac = false
@@ -203,7 +215,8 @@ if (current_os == "win" || current_os == "winrt_81" ||
   is_win = false
 } else if (current_os == "chromeos") {
   is_android = false
-  is_chromeos = true
+  assert(is_chromeos, "ChromiumOS requires is_chromeos.")
+  is_chromeos_os = true
   is_ios = false
   is_linux = true
   is_mac = false
@@ -215,7 +228,7 @@ if (current_os == "win" || current_os == "winrt_81" ||
   # It is not set by default or on the command line. We treat is as a
   # Posix variant.
   is_android = false
-  is_chromeos = false
+  is_chromeos_os = false
   is_ios = false
   is_linux = false
   is_mac = false
@@ -224,7 +237,7 @@ if (current_os == "win" || current_os == "winrt_81" ||
   is_win = false
 } else if (current_os == "ios") {
   is_android = false
-  is_chromeos = false
+  is_chromeos_os = false
   is_ios = true
   is_linux = false
   is_mac = false
@@ -233,7 +246,7 @@ if (current_os == "win" || current_os == "winrt_81" ||
   is_win = false
 } else if (current_os == "linux") {
   is_android = false
-  is_chromeos = false
+  is_chromeos_os = false
   is_ios = false
   is_linux = true
   is_mac = false
@@ -328,6 +341,8 @@ if (!is_android) {
     "*\bandroid/*",
   ]
 }
+
+#TODO(petermayo): Move this to features.gni with the removal of is_chromeos
 if (!is_chromeos) {
   sources_assignment_filter += [
     "*_chromeos.h",