Switch mash_browser_tests to Ozone X11 platform.

chrome/app/mash/BUILD.gn

Index: chrome/app/mash/BUILD.gn
diff --git a/chrome/app/mash/BUILD.gn b/chrome/app/mash/BUILD.gn
index 292a191979e2d30e630ba9ee6d8955be42438581..5f87d2ce89b5fba05563d71fdb9b3012e5385671 100644
--- a/chrome/app/mash/BUILD.gn
+++ b/chrome/app/mash/BUILD.gn
@@ -3,9 +3,12 @@
 # found in the LICENSE file.
 
 import("//build/config/nacl/config.gni")
+import("//chrome/common/features.gni")
 import("//services/catalog/public/tools/catalog.gni")
 import("//services/service_manager/public/service_manifest.gni")
 
+assert(enable_package_mash_services)
+
 source_set("mash") {
   sources = [
     "mash_runner.cc",
@@ -80,3 +83,10 @@ catalog_cpp_source("chrome_mash_catalog") {
   catalog = ":catalog"
   generated_function_name = "CreateChromeMashCatalog"
 }
+
+source_set("mash_service_overrides") {
+  testonly = true
+  data = [
+    "mash_service_overrides.json",
+  ]
+}