Rename is_chromeos in chrome/src.

sync/BUILD.gn

Index: sync/BUILD.gn
diff --git a/sync/BUILD.gn b/sync/BUILD.gn
index bf9e471177cd7a22d41d46421505d6107eab2d20..57e3450d36cb1ea7de5b029e6dc4d635bdd4a090 100644
--- a/sync/BUILD.gn
+++ b/sync/BUILD.gn
@@ -435,7 +435,7 @@ source_set("sync_core") {
     ]
   }
 
-  if (is_chromeos) {
+  if (use_cros_fe) {
     # Required by get_session_name.cc on Chrome OS.
     deps += [ "//chromeos" ]
   }
@@ -712,7 +712,7 @@ test("sync_unit_tests") {
     isolate_file = "sync_unit_tests.isolate"
   }
 
-  if (is_chromeos) {
+  if (use_cros_fe) {
     # Required by get_session_name_unittest.cc on Chrome OS.
     deps += [ "//chromeos" ]
   }