Add storage_unittests to buildbots.

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 5839c4698ac0065c54bc07af10aa03fe211d1b4e..fba413ded3508ba6f60691e94dbbe21ad93a2be8 100644
--- a/testing/buildbot/chromium.mac.json
+++ b/testing/buildbot/chromium.mac.json
@@ -13,6 +13,7 @@
       "printing_unittests",
       "skia_unittests",
       "sql_unittests",
+      "storage_unittests",
       "ui_base_unittests",
       "unit_tests",
       "url_unittests"
@@ -300,6 +301,12 @@
         "swarming": {
           "can_use_on_swarming_builders": true
         },
+        "test": "storage_unittests"
+      },
+      {
+        "swarming": {
+          "can_use_on_swarming_builders": true
+        },
         "test": "sync_integration_tests"
       },
       {
@@ -645,6 +652,12 @@
         "swarming": {
           "can_use_on_swarming_builders": true
         },
+        "test": "storage_unittests"
+      },
+      {
+        "swarming": {
+          "can_use_on_swarming_builders": true
+        },
         "test": "sync_integration_tests"
       },
       {
@@ -991,6 +1004,12 @@
         "swarming": {
           "can_use_on_swarming_builders": true
         },
+        "test": "storage_unittests"
+      },
+      {
+        "swarming": {
+          "can_use_on_swarming_builders": true
+        },
         "test": "sync_integration_tests"
       },
       {
@@ -1325,6 +1344,12 @@
         "swarming": {
           "can_use_on_swarming_builders": true
         },
+        "test": "storage_unittests"
+      },
+      {
+        "swarming": {
+          "can_use_on_swarming_builders": true
+        },
         "test": "sync_integration_tests"
       },
       {