TEST ONLY: Duplicate FP rather than modifying in place

content/common/feature_policy/feature_policy.cc

Index: content/common/feature_policy/feature_policy.cc
diff --git a/content/common/feature_policy/feature_policy.cc b/content/common/feature_policy/feature_policy.cc
index 0cf620b19da0fe6c8fe08230287796628f07bd1c..5ebdd7114f8e40fbe3d876e39599a798d21de0c5 100644
--- a/content/common/feature_policy/feature_policy.cc
+++ b/content/common/feature_policy/feature_policy.cc
@@ -86,6 +86,8 @@ ParsedFeaturePolicyDeclaration::~ParsedFeaturePolicyDeclaration() {}
 
 FeaturePolicy::Whitelist::Whitelist() : matches_all_origins_(false) {}
 
+FeaturePolicy::Whitelist::Whitelist(const Whitelist& rhs) = default;
+
 FeaturePolicy::Whitelist::~Whitelist() = default;
 
 void FeaturePolicy::Whitelist::Add(const url::Origin& origin) {
@@ -121,8 +123,18 @@ std::unique_ptr<FeaturePolicy> FeaturePolicy::CreateFromParentPolicy(
                                 GetDefaultFeatureList());
 }
 
-void FeaturePolicy::ResetOrigin(const url::Origin& origin) {
-  origin_ = url::Origin(origin);
+// static
+std::unique_ptr<FeaturePolicy> FeaturePolicy::CreateFromPolicyWithOrigin(
+    const FeaturePolicy& policy,
+    const url::Origin& origin) {
+  std::unique_ptr<FeaturePolicy> new_policy =
+      base::WrapUnique(new FeaturePolicy(origin, policy.feature_list_));
+  new_policy->inherited_policies_ = policy.inherited_policies_;
+  for (const auto& feature : policy.whitelists_) {
+    new_policy->whitelists_[feature.first] =
+        base::WrapUnique(new Whitelist(*feature.second));
+  }
+  return new_policy;
 }
 
 bool FeaturePolicy::IsFeatureEnabled(