Implement NavigationThrottle::BLOCK_REQUEST_AND_COLLAPSE.

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 7a4a0b9e20425f5b7d359840ccbc2d57f2dffbfc..57852cd2355fbce1ee58469dd51dea1415c9e9d5 100644
--- a/content/browser/frame_host/frame_tree_node.h
+++ b/content/browser/frame_host/frame_tree_node.h
@@ -145,6 +145,17 @@ class CONTENT_EXPORT FrameTreeNode {
     return has_committed_real_load_;
   }
 
+  // Returns whether the frame's owner element in the embedder document is

[nasko, 2017/03/01 20:08:04]

nit: s/embedder/parent/, it is a bit more web platform friendly name and
"embedder" is very overloaded term.

[engedy, 2017/04/10 14:36:41]

Done.

+  // collapsed, that is, removed from the layout as if it did not exist, as per
+  // request by the client.

[nasko, 2017/03/01 20:08:04]

What is "client" in this case? The content/ interface to chrome/? Or something
else?

[engedy, 2017/04/10 14:36:41]

Tried to clarify.

+  bool is_collapsed_by_client() const { return is_collapsed_by_client_; }
+
+  // Sets whether to collapse the frame's owner element in the embedder
+  // document, that is, to remove it from the layout as if it did not exist, as
+  // per request by the client. Cannot be called for main frames. Only has an
+  // effect for <iframe> owner elements.

[nasko, 2017/03/01 20:08:04]

Are there owner elements for things other than <iframe>? Maybe worthwhile adding
an example.

[engedy, 2017/04/10 14:36:41]

Done.

+  void SetCollapsedByClient(bool collapsed);
+
   // Returns the origin of the last committed page in this frame.
   // WARNING: To get the last committed origin for a particular
   // RenderFrameHost, use RenderFrameHost::GetLastCommittedOrigin() instead,
@@ -363,6 +374,12 @@ class CONTENT_EXPORT FrameTreeNode {
   // about:blank page.
   bool has_committed_real_load_;
 
+  // Whether the frame's owner element in the embedder document is collapsed,
+  // that is, removed from the layout as if it did not exist, as per request
+  // from the client. Always `false` for main frames. Only works for <iframe>
+  // owner elements.

[nasko, 2017/03/01 20:08:04]

nit: This comment is almost identical to the other two. Maybe keep the full
comment here and simplify the other two?

[engedy, 2017/04/10 14:36:41]

Actually, I made this one shorter.

+  bool is_collapsed_by_client_;
+
   // Track information that needs to be replicated to processes that have
   // proxies for this frame.
   FrameReplicationState replication_state_;