Adding latency_unittests to run on trybots.

testing/buildbot/chromium.memory.json

Index: testing/buildbot/chromium.memory.json
diff --git a/testing/buildbot/chromium.memory.json b/testing/buildbot/chromium.memory.json
index e206c3ffe35d86daa36f9f39cbe7c506831f9e6a..e73c1d63ca24690b12d5c5595628ca5844a0939a 100644
--- a/testing/buildbot/chromium.memory.json
+++ b/testing/buildbot/chromium.memory.json
@@ -465,6 +465,12 @@
         "swarming": {
           "can_use_on_swarming_builders": true
         },
+        "test": "latency_unittests"
+      },
+      {
+        "swarming": {
+          "can_use_on_swarming_builders": true
+        },
         "test": "media_blink_unittests"
       },
       {
@@ -761,6 +767,12 @@
         "swarming": {
           "can_use_on_swarming_builders": true
         },
+        "test": "latency_unittests"
+      },
+      {
+        "swarming": {
+          "can_use_on_swarming_builders": true
+        },
         "test": "media_blink_unittests"
       },
       {
@@ -1072,6 +1084,12 @@
         "swarming": {
           "can_use_on_swarming_builders": true
         },
+        "test": "latency_unittests"
+      },
+      {
+        "swarming": {
+          "can_use_on_swarming_builders": true
+        },
         "test": "media_blink_unittests"
       },
       {