Land a testing Finch config for the Chrome Sign in promo in the password bubble.

testing/variations/fieldtrial_testing_config_mac.json

 {
     "AutofillClassifier": [
         {
             "group_name": "Enabled"
         }
     ],
     "AutofillFieldMetadata": [
         {
             "group_name": "Enabled"
         }
@@ skipping 343 matching lines @@
     "SchedulerExpensiveTaskBlocking": [
         {
             "group_name": "Enabled"
         }
     ],
     "SdchPersistence": [
         {
             "group_name": "Enabled"
         }
     ],
+    "SignInPasswordPromo": [
+        {
+            "group_name": "Enable",
+            "params": {
+                "dismissal_threshold": "1"
+            }
+        }
+    ],
     "SimpleCacheTrial": [
         {
             "group_name": "ExperimentYes"
         }
     ],
     "StrictSecureCookies": [
         {
             "group_name": "Enabled"
         }
     ],
@@ skipping 89 matching lines @@
     ],
     "use-new-media-cache": [
         {
             "enable_features": [
                 "use-new-media-cache"
             ],
             "group_name": "Enabled"
         }
     ]
 }