Add a new experiment of GaiaPasswordReuse

Add a new experiment with warn_on_low_reputation set to true.

Change-Id: Iac7a2c1d1e91d2696011bb60beed2c81f1e2b1c7
Reviewed-on: https://chromium-review.googlesource.com/893905
Commit-Queue: Jialiu Lin <jialiul@chromium.org>
Reviewed-by: Ilya Sherman <isherman@chromium.org>
Cr-Commit-Position: refs/heads/master@{#533099}

testing/variations/fieldtrial_testing_config.json

@@ -1509,6 +1509,16 @@
                 "win"
             ],
             "experiments": [
+                {
+                    "name": "SofterWarningWarnOnLowReputation",
+                    "params": {
+                        "softer_warning": "true",
+                        "warn_on_low_reputation": "true"
+                    },
+                    "enable_features": [
+                        "PasswordProtectionGoogleBrandedPhishingWarning"
+                    ]
+                },
                 {
                     "name": "SofterWarning",
                     "params": {