Exclude reflector_impl_unittest.cc from GN non-Aura, non-Mac builds.

content/test/BUILD.gn

Index: content/test/BUILD.gn
diff --git a/content/test/BUILD.gn b/content/test/BUILD.gn
index 45bd97ca7e94c50c97856aead22b40801b1b4158..b8e13de22190d3b2af6e29722fa2d8629236eb80 100644
--- a/content/test/BUILD.gn
+++ b/content/test/BUILD.gn
@@ -595,6 +595,7 @@ if (!is_mac) {  # TODO(GYP) enable on Mac once it links.
     if (!use_aura && !is_mac) {
       sources -= [
         "../browser/compositor/buffer_queue_unittest.cc",
+        "../browser/compositor/reflector_impl_unittest.cc",
         "../browser/compositor/software_browser_compositor_output_surface_unittest.cc",
       ]
     }