media: Enable media_mojo_unittests on bots

BUILD.gn

Index: BUILD.gn
diff --git a/BUILD.gn b/BUILD.gn
index e3804a80685dc2fed4c321f46b5d0b04b4bdd4dd..bbc0dc7f8acf1dcfa53420bbf5af398ed3b7c93c 100644
--- a/BUILD.gn
+++ b/BUILD.gn
@@ -633,7 +633,10 @@ group("gn_only") {
   deps = []
 
   if (!is_ios) {
-    deps += [ "//mojo/common:mojo_common_perftests" ]
+    deps += [
+      "//media/mojo:media_mojo_unittests",
+      "//mojo/common:mojo_common_perftests",
+    ]
   }
 
   if (!is_android && !is_ios) {
@@ -783,8 +786,6 @@ group("gn_mojo_targets") {
     # and figure out how cross-platform they are
     deps = [
       "//ipc/mojo:ipc_mojo_perftests",
-      "//media/mojo:tests",
-      "//media/mojo/services",
       "//mojo:tests",
     ]
   }