Disable service_unittests on Mac Pros.

content/test/gpu/generate_buildbot_json.py

Index: content/test/gpu/generate_buildbot_json.py
diff --git a/content/test/gpu/generate_buildbot_json.py b/content/test/gpu/generate_buildbot_json.py
index 2bc0e427cc5b12e4e0cca5b1a1adcd018cab7289..640c34ed0f28665c53680c1e2f41e74833c31c44 100755
--- a/content/test/gpu/generate_buildbot_json.py
+++ b/content/test/gpu/generate_buildbot_json.py
@@ -1258,6 +1258,8 @@ COMMON_GTESTS = {
     ],
     'test': 'gles2_conform_test',
   },
+  # Face and barcode detection unit tests, which currently only run on
+  # Mac OS, and require physical hardware.
   'service_unittests': {
     'tester_configs': [
       {
@@ -1266,6 +1268,16 @@ COMMON_GTESTS = {
         'os_types': ['mac'],
       },
     ],
+    'disabled_tester_configs': [
+      {
+        'swarming_dimension_sets': [
+          # These tests fail on the Mac Pros.
+          {
+            'gpu': '1002:679e',
+          },
+        ],
+      },
+    ],
     'args': [
       '--gtest_filter=*Detection*',
       '--use-gpu-in-tests'