Rename is_chromeos in chrome/src.

build/config/sysroot.gni

Index: build/config/sysroot.gni
diff --git a/build/config/sysroot.gni b/build/config/sysroot.gni
index ffd8921f859a67ac12e56bbf119dfae55b3e563e..553e585c43cb2149afe0b4d1008e5b937d6895ca 100644
--- a/build/config/sysroot.gni
+++ b/build/config/sysroot.gni
@@ -5,6 +5,7 @@
 # This header file defines the "sysroot" variable which is the absolute path
 # of the sysroot. If no sysroot applies, the variable will be an empty string.
 
+import("//build/config/features.gni")
 import("//build/config/chrome_build.gni")
 
 declare_args() {
@@ -32,7 +33,7 @@ if (current_toolchain == default_toolchain && target_sysroot != "") {
   } else {
     sysroot = ""
   }
-} else if (is_linux && is_chrome_branded && is_official_build && !is_chromeos) {
+} else if (is_linux && is_chrome_branded && is_official_build && !use_cros_fe) {
   # For official builds, use the sysroot checked into the internal source repo
   # so that the builds work on older versions of Linux.
   if (current_cpu == "x64") {
@@ -43,7 +44,7 @@ if (current_toolchain == default_toolchain && target_sysroot != "") {
     # Any other builds don't use a sysroot.
     sysroot = ""
   }
-} else if (is_linux && !is_chromeos) {
+} else if (is_linux && !use_cros_fe) {
   if (current_cpu == "mipsel") {
     sysroot = rebase_path("//mipsel-sysroot/sysroot")
   } else {