Switch mash_browser_tests to Ozone X11 platform.

testing/buildbot/chromium.chromiumos.json

Index: testing/buildbot/chromium.chromiumos.json
diff --git a/testing/buildbot/chromium.chromiumos.json b/testing/buildbot/chromium.chromiumos.json
index 7e6fa3dd1927deae4233528f7a89014ae73dae27..fc44464b72303b2e7e15132fd025afd04bed66b6 100644
--- a/testing/buildbot/chromium.chromiumos.json
+++ b/testing/buildbot/chromium.chromiumos.json
@@ -64,22 +64,6 @@
         "test": "base_unittests"
       },
       {
-        "args": [
-          "--ozone-platform=headless",
-          "--override-use-gl-with-osmesa-for-tests",
-          "--run-in-mash",
-          "--service-overrides=src/chrome/app/mash/mash_service_overrides.json",
-          "--test-launcher-filter-file=src/testing/buildbot/filters/mash.browser_tests.filter",
-          "--use-test-config"
-        ],
-        "hard_timeout": 60,
-        "name": "mash_browser_tests",
-        "swarming": {
-          "can_use_on_swarming_builders": false
-        },
-        "test": "browser_tests"
-      },
-      {
         "swarming": {
           "can_use_on_swarming_builders": true
         },
@@ -235,6 +219,16 @@
         "test": "jingle_unittests"
       },
       {
+        "args": [
+          "--test-launcher-filter-file=../../testing/buildbot/filters/mash.browser_tests.filter"
+        ],
+        "hard_timeout": 60,
+        "swarming": {
+          "can_use_on_swarming_builders": true
+        },
+        "test": "mash_browser_tests"
+      },
+      {
         "swarming": {
           "can_use_on_swarming_builders": true
         },