Use Xvfb in isolated testing only if use_x11 is set

ui/message_center/message_center_unittests.isolate

Index: ui/message_center/message_center_unittests.isolate
diff --git a/ui/message_center/message_center_unittests.isolate b/ui/message_center/message_center_unittests.isolate
index 7ad8cc3cf6d9b645cc367a17465e867d15ac5ef7..18ad7162837a71087ebc5e923a1e03ce863cc085 100644
--- a/ui/message_center/message_center_unittests.isolate
+++ b/ui/message_center/message_center_unittests.isolate
@@ -12,7 +12,19 @@
         ],
       },
     }],
-    ['OS=="linux"', {
+    ['use_x11==0', {
+      'variables': {
+        'command': [
+          '../../testing/test_env.py',
+          '<(PRODUCT_DIR)/message_center_unittests<(EXECUTABLE_SUFFIX)',
+          '--brave-new-test-launcher',
+          '--test-launcher-bot-mode',
+          '--asan=<(asan)',
+          '--lsan=<(lsan)',
+        ],
+      },
+    }],
+    ['use_x11==1', {
       'variables': {
         'command': [
           '../../testing/xvfb.py',
@@ -25,14 +37,14 @@
         ],
         'files': [
           '../../testing/xvfb.py',
-          '<(PRODUCT_DIR)/libosmesa.so',
+          '<(PRODUCT_DIR)/xdisplaycheck<(EXECUTABLE_SUFFIX)',
         ],
       },
     }],
-    ['OS=="linux" and use_ozone==0', {
+    ['OS=="linux"', {
       'variables': {
         'files': [
-          '<(PRODUCT_DIR)/xdisplaycheck<(EXECUTABLE_SUFFIX)',
+          '<(PRODUCT_DIR)/libosmesa.so',
         ],
       },
     }],
@@ -50,18 +62,6 @@
         ],
       },
     }],
-    ['OS=="mac" or OS=="win"', {
-      'variables': {
-        'command': [
-          '../../testing/test_env.py',
-          '<(PRODUCT_DIR)/message_center_unittests<(EXECUTABLE_SUFFIX)',
-          '--brave-new-test-launcher',
-          '--test-launcher-bot-mode',
-          '--asan=<(asan)',
-          '--lsan=<(lsan)',
-        ],
-      },
-    }],
   ],
   'includes': [
     '../../base/base.isolate',