Implement NavigationThrottle::BLOCK_REQUEST_AND_COLLAPSE.

content/browser/frame_host/navigation_request.cc

Index: content/browser/frame_host/navigation_request.cc
diff --git a/content/browser/frame_host/navigation_request.cc b/content/browser/frame_host/navigation_request.cc
index 9f676eb677e923edb349021448e6600222f3df1e..ebb1f327511e7a20f494a2200d27bbf3302d1dce 100644
--- a/content/browser/frame_host/navigation_request.cc
+++ b/content/browser/frame_host/navigation_request.cc
@@ -580,6 +580,14 @@ void NavigationRequest::OnStartChecksComplete(
     return;
   }
 
+  if (result == NavigationThrottle::BLOCK_REQUEST_AND_COLLAPSE) {
+    frame_tree_node_->SetFrameOwnerCollapsedState(true);

[clamy, 2017/01/18 15:10:55]

Suggestion: maybe we could move this to the NavigationHandleImpl instead. This
would make it easier to work with the current implementation as well :).

[engedy, 2017/01/18 23:37:14]

Done.

+    OnRequestFailed(false, net::ERR_BLOCKED_BY_CLIENT);

[clamy, 2017/01/18 15:10:55]

Just checking: this means we will attempt to load an error page in the frame,
that won't show AFAIU since it is collapsed. Is that the expected behavior or
should we just cancel the request?

[engedy, 2017/01/18 23:37:14]

Yep, it is intended that we navigate away from the previously committed URL.

Implementation-wise, it seemed that triggering an error page is the simplest way
to get that behavior. Plus, this way the collapsed state is a function of the
last committed URL, which is nice. (IIUC the error page will commit under the
URL that errored out.)

I was considering adding a new error code so that this error page would be
emptier, but I am not sure if it makes a significant difference.

+    // DO NOT ADD CODE after this. The previous call to OnRequestFailed has
+    // destroyed the NavigationRequest.
+    return;
+  }
+
   // Use the SiteInstance of the navigating RenderFrameHost to get access to
   // the StoragePartition. Using the url of the navigation will result in a
   // wrong StoragePartition being picked when a WebView is navigating.
@@ -666,6 +674,14 @@ void NavigationRequest::OnRedirectChecksComplete(
     return;
   }
 
+  if (result == NavigationThrottle::BLOCK_REQUEST_AND_COLLAPSE) {
+    frame_tree_node_->SetFrameOwnerCollapsedState(true);
+    OnRequestFailed(false, net::ERR_BLOCKED_BY_CLIENT);
+    // DO NOT ADD CODE after this. The previous call to OnRequestFailed has
+    // destroyed the NavigationRequest.
+    return;
+  }
+
   loader_->FollowRedirect();
 }