Rename is_chromeos in chrome/src.

content/test/BUILD.gn

Index: content/test/BUILD.gn
diff --git a/content/test/BUILD.gn b/content/test/BUILD.gn
index d889c054bb0fa7c7188dafb23a4569d231172f35..f2ba392f5bfbefd0a5a7e4753cc8e9ac8e92e963 100644
--- a/content/test/BUILD.gn
+++ b/content/test/BUILD.gn
@@ -601,7 +601,7 @@ test("content_unittests") {
       deps += [ "//third_party/webrtc/modules/desktop_capture" ]
     }
 
-    if (is_chromeos) {
+    if (use_cros_fe) {
       sources +=
           [ "../browser/media/capture/desktop_capture_device_aura_unittest.cc" ]
     }
@@ -639,7 +639,7 @@ test("content_unittests") {
 
     deps += [ "//third_party/ocmock" ]
   }
-  if (is_chromeos) {
+  if (use_cros_fe) {
     sources -= [ "../browser/geolocation/wifi_data_provider_linux_unittest.cc" ]
     deps += [ "//chromeos" ]
   }