Add fieldtrial config for SmartDimNewMlAgent

Adding config before experiment/rollout to Beta in M84.

Bug: 1067048
Change-Id: I4544f4d65b413926b039b8896ac100711c53614e
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2235579Reviewed-by: Andrew Moylan <amoylan@chromium.org>
Reviewed-by: Steven Holte <holte@chromium.org>
Commit-Queue: Xinglong Luan <alanlxl@chromium.org>
Cr-Commit-Position: refs/heads/master@{#776821}

testing/variations/fieldtrial_testing_config.json

@@ -6111,6 +6111,21 @@
             ]
         }
     ],
+    "SmartDimNewMlAgent": [
+        {
+            "platforms": [
+                "chromeos"
+            ],
+            "experiments": [
+                {
+                    "name": "Enabled_20200609",
+                    "enable_features": [
+                        "SmartDimNewMlAgent"
+                    ]
+                }
+            ]
+        }
+    ],
     "SplitCacheByNetworkIsolationKey": [
         {
             "platforms": [