Rename is_chromeos in chrome/src.

base/BUILD.gn

Index: base/BUILD.gn
diff --git a/base/BUILD.gn b/base/BUILD.gn
index ccb580f1dab092a83d7307956864eabd033b4c53..5125265275e856bb10316ef1d944ced59f3dd265 100644
--- a/base/BUILD.gn
+++ b/base/BUILD.gn
@@ -710,7 +710,7 @@ component("base") {
     libs = [ "log" ]
   }
 
-  if (is_chromeos) {
+  if (use_cros_fe) {
     sources -= [ "power_monitor/power_monitor_device_source_posix.cc" ]
   }
 
@@ -1020,7 +1020,7 @@ component("i18n") {
   configs += [ "//build/config/compiler:no_size_t_to_int_warning" ]
 }
 
-if (is_ios || is_win || (is_linux && !is_chromeos)) {
+if (is_ios || is_win || is_desktop_linux) {
   # TODO(GYP): Figure out which of these work and are needed on other platforms.
   test("base_perftests") {
     sources = [