Add xvfb logic to all windowed test launcher targets.

The "generic_wrapper" scripts now being generated during the build
need to know whether or not to use Xvfb when running a test; this
CL adds that logic.

Bug: 816629
Change-Id: Ic2cae1295d7edf583236d6d2640c220c883324ed
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2370507
Commit-Queue: Dirk Pranke <dpranke@google.com>
Reviewed-by: Scott Violet <sky@chromium.org>
Reviewed-by: Yuke Liao <liaoyuke@chromium.org>
Cr-Commit-Position: refs/heads/master@{#802875}

diff --git a/ui/aura/BUILD.gn b/ui/aura/BUILD.gn
index 0b7516f..c1dbce0d 100644
--- a/ui/aura/BUILD.gn
+++ b/ui/aura/BUILD.gn

@@ -314,9 +314,7 @@
 }
 
 test("aura_unittests") {
-  if ((is_linux && !is_chromeos) || chromeos_is_browser_only) {
-    use_xvfb = true
-  }
+  use_xvfb = use_xvfb_in_this_config
 
   sources = [
     "../compositor_extra/shadow_unittest.cc",