Convert ppapi_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 8000df44c1b6a6b479830456aa4f67e9f2b9b23a..64a7d7a46a6fdc1bb1cff865334838736e40492e 100644
--- a/testing/buildbot/chromium.mac.json
+++ b/testing/buildbot/chromium.mac.json
@@ -192,6 +192,9 @@
         "test": "net_unittests"
       },
       {
+        "swarming": {
+          "can_use_on_swarming_builders": true
+        },
         "test": "ppapi_unittests"
       },
       {
@@ -424,6 +427,9 @@
         "test": "net_unittests"
       },
       {
+        "swarming": {
+          "can_use_on_swarming_builders": true
+        },
         "test": "ppapi_unittests"
       },
       {
@@ -668,6 +674,9 @@
         "test": "net_unittests"
       },
       {
+        "swarming": {
+          "can_use_on_swarming_builders": true
+        },
         "test": "ppapi_unittests"
       },
       {
@@ -912,6 +921,9 @@
         "test": "net_unittests"
       },
       {
+        "swarming": {
+          "can_use_on_swarming_builders": true
+        },
         "test": "ppapi_unittests"
       },
       {
@@ -1157,6 +1169,9 @@
         "test": "net_unittests"
       },
       {
+        "swarming": {
+          "can_use_on_swarming_builders": true
+        },
         "test": "ppapi_unittests"
       },
       {