Add fieldtrial testing config for ButterForPasswords

Bug: 991510
Change-Id: I447e99f11c322478f007557ab268823ed2616042
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/2455446
Commit-Queue: Jesse Doherty <jwd@chromium.org>
Auto-Submit: Marc Treib <treib@chromium.org>
Reviewed-by: Jesse Doherty <jwd@chromium.org>
Cr-Commit-Position: refs/heads/master@{#815355}

testing/variations/fieldtrial_testing_config.json

@@ -1262,6 +1262,29 @@
             ]
         }
     ],
+    "ButterForPasswords": [
+        {
+            "platforms": [
+                "linux",
+                "mac",
+                "windows"
+            ],
+            "experiments": [
+                {
+                    "name": "ButterForPasswords",
+                    "params": {
+                        "event_1": "name:passwords_account_storage_unselected;comparator:==0;window:180;storage:180",
+                        "event_trigger": "name:passwords_account_storage_trigger;comparator:<5;window:180;storage:180",
+                        "event_used": "name:passwords_account_storage_used;comparator:==0;window:180;storage:180"
+                    },
+                    "enable_features": [
+                        "EnablePasswordsAccountStorage",
+                        "IPH_PasswordsAccountStorage"
+                    ]
+                }
+            ]
+        }
+    ],
     "CSSMatchedPropertiesCacheDependencies": [
         {
             "platforms": [