Rename is_chromeos in chrome/src.

tools/perf/clear_system_cache/BUILD.gn

 # Copyright 2015 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # found in the LICENSE file.
 
-if (is_linux && !is_chromeos) {
-  # TODO(GYP): Figure out which of these work and are needed on other platforms.
-  executable("clear_system_cache") {
-    testonly = true
+if (is_linux) {
+  import("//build/config/features.gni")
+  if (!use_cros_fe) {
+    # TODO(GYP): Figure out which of these work and are needed on other platforms.
+    executable("clear_system_cache") {
+      testonly = true
 
-    sources = [
-      "clear_system_cache_main.cc",
-    ]
+      sources = [
+        "clear_system_cache_main.cc",
+      ]
 
-    deps = [
-      "//base",
-      "//base/test:test_support",
-    ]
+      deps = [
+        "//base",
+        "//base/test:test_support",
+      ]
+    }
   }
 }