[WIP NOT FOR COMMIT] Feature policy: Add basic algorithm for supporting frame policies, start plumb…

content/common/feature_policy/feature_policy.h

Index: content/common/feature_policy/feature_policy.h
diff --git a/content/common/feature_policy/feature_policy.h b/content/common/feature_policy/feature_policy.h
index 22b7d1b9b45036bc035e8fe1843c2026f7f5acf5..a03664be7a863e96eaa2abb14fd9c5f1c24e84cb 100644
--- a/content/common/feature_policy/feature_policy.h
+++ b/content/common/feature_policy/feature_policy.h
@@ -157,6 +157,7 @@ class CONTENT_EXPORT FeaturePolicy : public blink::WebFeaturePolicy {
 
   static std::unique_ptr<FeaturePolicy> CreateFromParentPolicy(
       const FeaturePolicy* parent_policy,
+      const FeaturePolicyHeader* frame_policy,
       url::Origin origin);
 
   // Returns whether or not the given feature is enabled by this policy.
@@ -178,9 +179,15 @@ class CONTENT_EXPORT FeaturePolicy : public blink::WebFeaturePolicy {
   FeaturePolicy(url::Origin origin, const FeatureList& feature_list);
   static std::unique_ptr<FeaturePolicy> CreateFromParentPolicy(
       const FeaturePolicy* parent_policy,
+      const FeaturePolicyHeader* frame_policy,
       url::Origin origin,
       const FeatureList& features);
 
+  // Updates the inherited policy with the declarations from the iframe allow*
+  // attributes.
+  void AddFramePolicy(const FeaturePolicy* parent_policy,
+                      const FeaturePolicyHeader* frame_policy);
+
   // Returns the list of features which can be controlled by Feature Policy.
   static const FeatureList& getDefaultFeatureList();