Add config for Chromium Mac 10.11 Force Mac Toolchain on chromium.fyi

testing/buildbot/chromium.fyi.json

 {
   "Android Cloud Tests": {
     "gtest_tests": [
       {
         "test": "android_webview_unittests"
       },
       {
         "test": "base_unittests"
       },
       {
@@ skipping 753 matching lines @@
         }
       }
     ],
     "scripts": [
       {
         "name": "nacl_integration",
         "script": "nacl_integration.py"
       }
     ]
   },
+  "Chromium Mac 10.11 Force Mac Toolchain": {
+    "gtest_tests": [
+      {
+        "test": "accessibility_unittests"
+      },
+      {
+        "test": "app_list_unittests"
+      },
+      {
+        "test": "base_unittests"
+      },
+      {
+        "test": "browser_tests"
+      },
+      {
+        "test": "cacheinvalidation_unittests"
+      },
+      {
+        "test": "cast_unittests"
+      },
+      {
+        "test": "cc_unittests"
+      },
+      {
+        "test": "chromedriver_unittests"
+      },
+      {
+        "test": "components_unittests"
+      },
+      {
+        "test": "content_browsertests"
+      },
+      {
+        "test": "content_unittests"
+      },
+      {
+        "test": "crypto_unittests"
+      },
+      {
+        "test": "extensions_unittests"
+      },
+      {
+        "test": "gcm_unit_tests"
+      },
+      {
+        "test": "gfx_unittests"
+      },
+      {
+        "test": "google_apis_unittests"
+      },
+      {
+        "test": "gpu_unittests"
+      },
+      {
+        "test": "interactive_ui_tests"
+      },
+      {
+        "test": "ipc_tests"
+      },
+      {
+        "test": "jingle_unittests"
+      },
+      {
+        "test": "media_blink_unittests"
+      },
+      {
+        "test": "media_unittests"
+      },
+      {
+        "test": "message_center_unittests"
+      },
+      {
+        "test": "midi_unittests"
+      },
+      {
+        "test": "mojo_common_unittests"
+      },
+      {
+        "test": "mojo_public_bindings_unittests"
+      },
+      {
+        "swarming": {
+          "can_use_on_swarming_builders": true
+        },
+        "test": "mojo_public_system_unittests"
+      },
+      {
+        "test": "mojo_system_unittests"
+      },
+      {
+        "test": "net_unittests"
+      },
+      {
+        "test": "ppapi_unittests"
+      },
+      {
+        "test": "printing_unittests"
+      },
+      {
+        "test": "remoting_unittests"
+      },
+      {
+        "test": "sandbox_mac_unittests"
+      },
+      {
+        "test": "skia_unittests"
+      },
+      {
+        "test": "sql_unittests"
+      },
+      {
+        "test": "sync_integration_tests"
+      },
+      {
+        "test": "sync_unit_tests"
+      },
+      {
+        "test": "ui_base_unittests"
+      },
+      {
+        "test": "unit_tests"
+      },
+      {
+        "test": "url_unittests"
+      }
+    ],
+    "scripts": [
+      {
+        "name": "nacl_integration",
+        "script": "nacl_integration.py"
+      }
+    ]
+  },
   "Chromium Win 10": {
     "gtest_tests": [
       {
         "swarming": {
           "can_use_on_swarming_builders": true
         },
         "test": "angle_unittests"
       },
       {
         "swarming": {
@@ skipping 6913 matching lines @@
       },
       {
         "args": [
           "--isolate-extensions"
         ],
         "test": "unit_tests"
       }
     ]
   }
 }