Adding latency_unittests to run on trybots.

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 f77ce489cb182cfdeb8bd9506efdd9963f902990..e555670cc747f65bcb0691b3fde52c38bb320787 100644
--- a/testing/buildbot/chromium.win.json
+++ b/testing/buildbot/chromium.win.json
@@ -229,6 +229,12 @@
         "swarming": {
           "can_use_on_swarming_builders": true
         },
+        "test": "latency_unittests"
+      },
+      {
+        "swarming": {
+          "can_use_on_swarming_builders": true
+        },
         "test": "libjingle_xmpp_unittests"
       },
       {
@@ -790,6 +796,12 @@
         "swarming": {
           "can_use_on_swarming_builders": true
         },
+        "test": "latency_unittests"
+      },
+      {
+        "swarming": {
+          "can_use_on_swarming_builders": true
+        },
         "test": "libjingle_xmpp_unittests"
       },
       {
@@ -1267,6 +1279,12 @@
         "swarming": {
           "can_use_on_swarming_builders": true
         },
+        "test": "latency_unittests"
+      },
+      {
+        "swarming": {
+          "can_use_on_swarming_builders": true
+        },
         "test": "libjingle_xmpp_unittests"
       },
       {
@@ -1712,6 +1730,12 @@
         "swarming": {
           "can_use_on_swarming_builders": true
         },
+        "test": "latency_unittests"
+      },
+      {
+        "swarming": {
+          "can_use_on_swarming_builders": true
+        },
         "test": "libjingle_xmpp_unittests"
       },
       {