Add OptimizationTargetPrediction to fieldtrials.

Bug: 1041908
Change-Id: I15dda3f992b930bb7280a3c16639c47d2b054680
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2001285
Commit-Queue: Michael Crouse <mcrouse@chromium.org>
Reviewed-by: Tarun Bansal <tbansal@chromium.org>
Reviewed-by: Sophie Chang <sophiechang@chromium.org>
Cr-Commit-Position: refs/heads/master@{#732561}

testing/variations/fieldtrial_testing_config.json

@@ -4367,6 +4367,24 @@
             ]
         }
     ],
+    "OptimizationTargetPrediction": [
+        {
+            "platforms": [
+                "android"
+            ],
+            "experiments": [
+                {
+                    "name": "Enabled",
+                    "params": {
+                        "max_effective_connection_type_for_navigation_hints_fetch": "4G"
+                    },
+                    "enable_features": [
+                        "OptimizationTargetPrediction"
+                    ]
+                }
+            ]
+        }
+    ],
     "OutOfBlinkCors": [
         {
             "platforms": [