Use Xvfb in isolated testing only if use_x11 is set

ui/events/events_unittests.isolate

Index: ui/events/events_unittests.isolate
diff --git a/ui/events/events_unittests.isolate b/ui/events/events_unittests.isolate
index 024de78a2061f96290d6f4e5d96a5c04e41cab39..269af58c202f36a60f3c068fce203f6b58ef14ef 100644
--- a/ui/events/events_unittests.isolate
+++ b/ui/events/events_unittests.isolate
@@ -11,7 +11,7 @@
         ],
       },
     }],
-    ['OS=="linux"', {
+    ['OS=="linux" and use_ozone==1', {
       'variables': {
         'command': [
           '../../testing/xvfb.py',
@@ -24,14 +24,14 @@
         ],
         'files': [
           '../../testing/xvfb.py',
-          '<(PRODUCT_DIR)/libosmesa.so',
+          '<(PRODUCT_DIR)/xdisplaycheck<(EXECUTABLE_SUFFIX)',
         ],
       },
     }],
     ['OS=="linux" and use_ozone==0', {
       'variables': {
         'files': [
-          '<(PRODUCT_DIR)/xdisplaycheck<(EXECUTABLE_SUFFIX)',
+          '<(PRODUCT_DIR)/libosmesa.so',
         ],
       },
     }],
@@ -49,7 +49,7 @@
         ],
       },
     }],
-    ['OS=="mac" or OS=="win"', {
+    ['OS=="mac" or OS=="win" or use_ozone==1', {
       'variables': {
         'command': [
           '../../testing/test_env.py',