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 d2fbf75ee90dd0d186499c6fa1a7912131346e2b..26cf486787522224c94cb41a7cf5f0bf9185f6de 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": "media_blink_unittests"
       },
       {
@@ -784,6 +790,12 @@
         "swarming": {
           "can_use_on_swarming_builders": true
         },
+        "test": "latency_unittests"
+      },
+      {
+        "swarming": {
+          "can_use_on_swarming_builders": true
+        },
         "test": "media_blink_unittests"
       },
       {
@@ -1255,6 +1267,12 @@
         "swarming": {
           "can_use_on_swarming_builders": true
         },
+        "test": "latency_unittests"
+      },
+      {
+        "swarming": {
+          "can_use_on_swarming_builders": true
+        },
         "test": "media_blink_unittests"
       },
       {
@@ -1694,6 +1712,12 @@
         "swarming": {
           "can_use_on_swarming_builders": true
         },
+        "test": "latency_unittests"
+      },
+      {
+        "swarming": {
+          "can_use_on_swarming_builders": true
+        },
         "test": "media_blink_unittests"
       },
       {