Use Xvfb in isolated testing only if use_x11 is set

chrome/browser_tests.isolate

Index: chrome/browser_tests.isolate
diff --git a/chrome/browser_tests.isolate b/chrome/browser_tests.isolate
index 49569770c2c9d93d29f811450bf11d9f5d2595e6..452fa20763684a1e4517845afb413280f98662af 100644
--- a/chrome/browser_tests.isolate
+++ b/chrome/browser_tests.isolate
@@ -3,7 +3,7 @@
 # found in the LICENSE file.
 {
   'conditions': [
-    ['OS=="linux"', {
+    ['OS=="linux" and use_x11==1', {
       'variables': {
         'command': [
           '../testing/xvfb.py',
@@ -15,16 +15,16 @@
         ],
         'files': [
           '../testing/xvfb.py',
-          '<(PRODUCT_DIR)/libclearkeycdm.so',
-          '<(PRODUCT_DIR)/libclearkeycdmadapter.so',
-          '<(PRODUCT_DIR)/libppapi_tests.so',
+          '<(PRODUCT_DIR)/xdisplaycheck<(EXECUTABLE_SUFFIX)',
         ],
       },
     }],
-    ['OS=="linux" and use_ozone==0', {
+    ['OS=="linux"', {
       'variables': {
         'files': [
-          '<(PRODUCT_DIR)/xdisplaycheck<(EXECUTABLE_SUFFIX)',
+          '<(PRODUCT_DIR)/libclearkeycdm.so',
+          '<(PRODUCT_DIR)/libclearkeycdmadapter.so',
+          '<(PRODUCT_DIR)/libppapi_tests.so',
         ],
       },
     }],
@@ -158,7 +158,7 @@
         ],
       },
     }],
-    ['OS=="mac" or OS=="win"', {
+    ['OS=="mac" or OS=="win" or use_ozone==1', {
       'variables': {
         'command': [
           '../testing/test_env.py',