Convert ui_base_unittests to run exclusively on Swarming

testing/buildbot/chromium.win.json

Index: testing/buildbot/chromium.win.json
diff --git a/testing/buildbot/chromium.win.json b/testing/buildbot/chromium.win.json
index a3a338736fd0a8d2823eae0de73498aec83bc169..eb3640d27b6a780f4e049b6bfc7c1f9193d0b0c7 100644
--- a/testing/buildbot/chromium.win.json
+++ b/testing/buildbot/chromium.win.json
@@ -205,6 +205,9 @@
         "test": "sync_unit_tests"
       },
       {
+        "swarming": {
+          "can_use_on_swarming_builders": true
+        },
         "test": "ui_base_unittests"
       },
       {
@@ -464,6 +467,9 @@
         "test": "sync_unit_tests"
       },
       {
+        "swarming": {
+          "can_use_on_swarming_builders": true
+        },
         "test": "ui_base_unittests"
       },
       {
@@ -842,6 +848,9 @@
         "test": "sync_unit_tests"
       },
       {
+        "swarming": {
+          "can_use_on_swarming_builders": true
+        },
         "test": "ui_base_unittests"
       },
       {
@@ -1080,6 +1089,9 @@
         "test": "sync_unit_tests"
       },
       {
+        "swarming": {
+          "can_use_on_swarming_builders": true
+        },
         "test": "ui_base_unittests"
       },
       {
@@ -1476,6 +1488,9 @@
         "test": "sync_unit_tests"
       },
       {
+        "swarming": {
+          "can_use_on_swarming_builders": true
+        },
         "test": "ui_base_unittests"
       },
       {