Switch mash_browser_tests to Ozone X11 platform.

chrome/app/mash/BUILD.gn

 # Copyright 2016 The Chromium Authors. All rights reserved.
 # Use of this source code is governed by a BSD-style license that can be
 # 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",
     "mash_runner.h",
   ]
   deps = [
     ":chrome_mash_catalog",
     "//base:i18n",
     "//components/tracing:startup_tracing",
     "//content/public/common",
@@ skipping 54 matching lines @@
 
 catalog("catalog") {
   embedded_services = [ ":mash_manifest" ]
   catalog_deps = [ "//chrome/app:catalog" ]
 }
 
 catalog_cpp_source("chrome_mash_catalog") {
   catalog = ":catalog"
   generated_function_name = "CreateChromeMashCatalog"
 }
+
+source_set("mash_service_overrides") {
+  testonly = true
+  data = [
+    "mash_service_overrides.json",
+  ]
+}