Convert events_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 ea87425b39f24ab305694434a36a46c351fdd9d9..3dd4c0afdbbd0b18f3e02344ef42f1df5f048cf0 100644
--- a/testing/buildbot/chromium.win.json
+++ b/testing/buildbot/chromium.win.json
@@ -81,6 +81,9 @@
         "test": "crypto_unittests"
       },
       {
+        "swarming": {
+          "can_use_on_swarming_builders": true
+        },
         "test": "events_unittests"
       },
       {
@@ -328,6 +331,9 @@
         "test": "device_unittests"
       },
       {
+        "swarming": {
+          "can_use_on_swarming_builders": true
+        },
         "test": "events_unittests"
       },
       {
@@ -700,6 +706,9 @@
         "test": "device_unittests"
       },
       {
+        "swarming": {
+          "can_use_on_swarming_builders": true
+        },
         "test": "events_unittests"
       },
       {
@@ -952,6 +961,9 @@
         "test": "crypto_unittests"
       },
       {
+        "swarming": {
+          "can_use_on_swarming_builders": true
+        },
         "test": "events_unittests"
       },
       {
@@ -1349,6 +1361,9 @@
         "test": "crypto_unittests"
       },
       {
+        "swarming": {
+          "can_use_on_swarming_builders": true
+        },
         "test": "events_unittests"
       },
       {