OOPIF: Remove the FrameTreeNode when a RemoteFrame is detached.

content/browser/frame_host/frame_tree_node.h

Index: content/browser/frame_host/frame_tree_node.h
diff --git a/content/browser/frame_host/frame_tree_node.h b/content/browser/frame_host/frame_tree_node.h
index 458887baaf6403ba538c8775fadf7fbf695e1ba6..ede2cd1dbdc4108cf1742ef11621e5576fc95abc 100644
--- a/content/browser/frame_host/frame_tree_node.h
+++ b/content/browser/frame_host/frame_tree_node.h
@@ -112,6 +112,11 @@ class CONTENT_EXPORT FrameTreeNode {
     return replication_state_.origin.IsSameAs(node.replication_state_.origin);
   }
 
+  // Returns whether this node has any ancestor FrameTreeNode with a current
+  // RenderFrameHost in |site_instance|.  This is useful for determining if
+  // messages from the SiteInstance's process have "ownership" over this frame.
+  bool HasAncestorFrom(SiteInstance* site_instance) const;
+
   const FrameReplicationState& current_replication_state() const {
     return replication_state_;
   }