Move container policy logic to frame owner classes.

third_party/WebKit/Source/core/html/HTMLFrameOwnerElement.h

Index: third_party/WebKit/Source/core/html/HTMLFrameOwnerElement.h
diff --git a/third_party/WebKit/Source/core/html/HTMLFrameOwnerElement.h b/third_party/WebKit/Source/core/html/HTMLFrameOwnerElement.h
index 57d3a7bb1f5a4c5259d145984f0ae9187854825c..3564d38449c7f1f27a4e817cd7885d91501aa52b 100644
--- a/third_party/WebKit/Source/core/html/HTMLFrameOwnerElement.h
+++ b/third_party/WebKit/Source/core/html/HTMLFrameOwnerElement.h
@@ -126,9 +126,16 @@ class CORE_EXPORT HTMLFrameOwnerElement : public HTMLElement,
     return SecurityOrigin::CreateUnique();
   }
 
-  // Construct a new feature policy container policy for this frame, based on
-  // the frame attributes and the effective origin specified in the frame
-  // attributes.
+  // Return a feature policy container policy for this frame, based on the
+  // frame attributes and the effective origin specified in the frame
+  // attributes. The base implementation here uses the "allow" attribute, but
+  // additional attributes and or restrictions may be introduced by specific
+  // frame classses.
+  virtual Vector<WebParsedFeaturePolicyDeclaration> ConstructContainerPolicy()
+      const;
+
+  // Update the container policy and notify the frame loader client of any
+  // changes.
   void UpdateContainerPolicy();
 
  private: