Use Xvfb in isolated testing only if use_x11 is set

chrome/browser_tests.isolate

 # Copyright (c) 2012 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.
 {
   'conditions': [
-    ['OS=="linux"', {
+    ['OS=="linux" and use_x11==1', {
       'variables': {
         'command': [
           '../testing/xvfb.py',
           '<(PRODUCT_DIR)',
           '<(PRODUCT_DIR)/browser_tests<(EXECUTABLE_SUFFIX)',
           '--test-launcher-bot-mode',
           '--asan=<(asan)',
           '--lsan=<(lsan)',
         ],
         'files': [
           '../testing/xvfb.py',
+          '<(PRODUCT_DIR)/xdisplaycheck<(EXECUTABLE_SUFFIX)',
+        ],
+      },
+    }],
+    ['OS=="linux"', {
+      'variables': {
+        'files': [
           '<(PRODUCT_DIR)/libclearkeycdm.so',
           '<(PRODUCT_DIR)/libclearkeycdmadapter.so',
           '<(PRODUCT_DIR)/libppapi_tests.so',
         ],
       },
     }],
-    ['OS=="linux" and use_ozone==0', {
-      'variables': {
-        'files': [
-          '<(PRODUCT_DIR)/xdisplaycheck<(EXECUTABLE_SUFFIX)',
-        ],
-      },
-    }],
     ['OS=="linux" and libpeer_target_type=="loadable_module"', {
       'variables': {
         'files': [
           '<(PRODUCT_DIR)/lib/libpeerconnection.so',
         ],
       },
     }],
     ['OS=="linux" or OS=="mac" or OS=="win"', {
       'variables': {
         'files': [
@@ skipping 110 matching lines @@
           '<(PRODUCT_DIR)/clearkeycdmadapter.plugin',
           '<(PRODUCT_DIR)/content_shell.pak',
           '<(PRODUCT_DIR)/libclearkeycdm.dylib',
           '<(PRODUCT_DIR)/osmesa.so',
           '<(PRODUCT_DIR)/plugins/npapi_test_plugin.plugin/',
           '<(PRODUCT_DIR)/plugins/test_netscape_plugin.plugin/',
           '<(PRODUCT_DIR)/ppapi_tests.plugin/Contents/MacOS/ppapi_tests',
         ],
       },
     }],
-    ['OS=="mac" or OS=="win"', {
+    ['OS=="mac" or OS=="win" or use_ozone==1', {
       'variables': {
         'command': [
           '../testing/test_env.py',
           '<(PRODUCT_DIR)/browser_tests<(EXECUTABLE_SUFFIX)',
           '--test-launcher-bot-mode',
           '--asan=<(asan)',
           '--lsan=<(lsan)',
         ],
       },
     }],
@@ skipping 52 matching lines @@
           'browser/chromeos/login/test/https_forwarder.py',
         ],
       },
     }],
   ],
   'includes': [
     '../base/base.isolate',
     'chrome.isolate',
   ],
 }