Adds more BUILD.gns to ash

ash/common/test/ash_test.h

Index: ash/common/test/ash_test.h
diff --git a/ash/common/test/ash_test.h b/ash/common/test/ash_test.h
index 8f44db26c4ac11d64fbaa105057e72a80f480d69..960d9543677d98e8968824fab332bd7cfb8da25d 100644
--- a/ash/common/test/ash_test.h
+++ b/ash/common/test/ash_test.h
@@ -49,8 +49,8 @@ class WindowOwner {
 // ash/common and run in both mus and aura.
 //
 // The implementation of AshTestImpl that is used depends upon gn targets. To
-// use the aura backend depend on "//ash:ash_with_aura_test_support." The mus
-// backend is not provided as a separate link target.
+// use the aura backend depend on "//ash/test:ash_with_aura_test_support." The
+// mus backend is not provided as a separate link target.
 class AshTest : public testing::Test {
  public:
   AshTest();