Add support for multiple simultaneous subresource_filter::Configurations.

testing/variations/fieldtrial_testing_config.json

 {
     "AlternateComponentUrls": [
         {
             "platforms": [
                 "android",
                 "chromeos",
                 "ios",
                 "linux",
                 "mac",
                 "win"
@@ skipping 2925 matching lines @@
                 "android",
                 "chromeos",
                 "linux",
                 "mac",
                 "win"
             ],
             "experiments": [
                 {
                     "name": "EnabledForPhishingSites",
                     "params": {
-                        "activation_lists": "phishing_interstitial",
-                        "activation_scope": "activation_list",
-                        "activation_state": "enabled"
+                        "enable_presets": "liverun_on_phishing_sites"
                     },
                     "enable_features": [
                         "SubresourceFilter"
                     ]
                 },
                 {
                     "name": "VerifyFeatureIsStillDisabledByDefault",
                     "forcing_flag": "suppress-enabling-subresource-filter-from-fieldtrial-testing-config"
                 }
             ]
@@ skipping 455 matching lines @@
                 {
                     "name": "Enabled",
                     "enable_features": [
                         "use-new-media-cache"
                     ]
                 }
             ]
         }
     ]
 }