Enable V4LocalDatabaseManager based on Finch.

testing/variations/fieldtrial_testing_config_win.json

 {
     "AutofillClassifier": [
         {
             "group_name": "Enabled"
         }
     ],
     "AutofillFieldMetadata": [
         {
             "group_name": "Enabled"
         }
@@ skipping 308 matching lines @@
         }
     ],
     "SafeBrowsingUpdateFrequency": [
         {
             "group_name": "UpdateTime15m",
             "params": {
                 "NextUpdateIntervalInMinutes": "15"
             }
         }
     ],
+    "SafeBrowsingV4LocalDatabaseManagerEnabled": [
+        {
+            "group_name": "Enabled"
+        }
+    ],
     "SchedulerExpensiveTaskBlocking": [
         {
             "group_name": "Enabled"
         }
     ],
     "SdchPersistence": [
         {
             "group_name": "Enabled"
         }
     ],
@@ skipping 66 matching lines @@
     ],
     "use-new-media-cache": [
         {
             "enable_features": [
                 "use-new-media-cache"
             ],
             "group_name": "Enabled"
         }
     ]
 }