headless: Add gn settings for embedded build and headless mode

chrome/test/BUILD.gn

Index: chrome/test/BUILD.gn
diff --git a/chrome/test/BUILD.gn b/chrome/test/BUILD.gn
index 815f2b6d45fc9eef976ef9fb93021cf3d61f77a4..cd61ac3c208c293d4bd0827e49f758f1053d4c9c 100644
--- a/chrome/test/BUILD.gn
+++ b/chrome/test/BUILD.gn
@@ -1104,7 +1104,7 @@ if (!is_android) {
         "../browser/media_galleries/fileapi/iapps_finder_impl_win_browsertest.cc",
       ]
     }
-    if (!is_chromeos && use_aura) {
+    if (!is_chromeos && use_aura && use_ash) {
       sources -= [
         # On Windows and Linux, we currently don't support enough of the
         # ash environment to run these unit tests.