Convert mojo_public_bindings_unittests to run exclusively on Swarming

testing/buildbot/chromium.mac.json

Index: testing/buildbot/chromium.mac.json
diff --git a/testing/buildbot/chromium.mac.json b/testing/buildbot/chromium.mac.json
index eb23427e7eee8804abb09f342a2d91f52c5b2ad2..400370814675d718df09ce02e7a68278a6f69545 100644
--- a/testing/buildbot/chromium.mac.json
+++ b/testing/buildbot/chromium.mac.json
@@ -192,6 +192,9 @@
         "test": "mojo_common_unittests"
       },
       {
+        "swarming": {
+          "can_use_on_swarming_builders": true
+        },
         "test": "mojo_public_bindings_unittests"
       },
       {
@@ -440,6 +443,9 @@
         "test": "mojo_common_unittests"
       },
       {
+        "swarming": {
+          "can_use_on_swarming_builders": true
+        },
         "test": "mojo_public_bindings_unittests"
       },
       {
@@ -697,6 +703,9 @@
         "test": "mojo_common_unittests"
       },
       {
+        "swarming": {
+          "can_use_on_swarming_builders": true
+        },
         "test": "mojo_public_bindings_unittests"
       },
       {
@@ -954,6 +963,9 @@
         "test": "mojo_common_unittests"
       },
       {
+        "swarming": {
+          "can_use_on_swarming_builders": true
+        },
         "test": "mojo_public_bindings_unittests"
       },
       {
@@ -1212,6 +1224,9 @@
         "test": "mojo_common_unittests"
       },
       {
+        "swarming": {
+          "can_use_on_swarming_builders": true
+        },
         "test": "mojo_public_bindings_unittests"
       },
       {