Navigation: Added a browser-initiated NavigationClient disconnect handler.

Currently, browser initiated navigations are never interrupted after
binding the remote NavigationClient. This does not handle cases where
the failure happens after ReadyToCommit.

For example a download to a source url would be flagged as illegal in
the blink frame and the DocumentLoader destructed, which should notify
the browser.

Bug: 784904
Change-Id: Idd39bbf702ad2cb53b1b0eb1c01ca1df7b58124c
Reviewed-on: https://chromium-review.googlesource.com/c/1494888Reviewed-by: Camille Lamy <clamy@chromium.org>
Commit-Queue: Arthur Hemery <ahemery@chromium.org>
Cr-Commit-Position: refs/heads/master@{#636775}

content/browser/frame_host/navigation_request.cc

@@ -839,8 +839,14 @@ void NavigationRequest::RegisterSubresourceOverride(
 mojom::NavigationClient* NavigationRequest::GetCommitNavigationClient() {
   if (commit_navigation_client_ && commit_navigation_client_.is_bound())
     return commit_navigation_client_.get();
+
+  // Instantiate a new NavigationClient interface.
   commit_navigation_client_ =
       render_frame_host_->GetNavigationClientFromInterfaceProvider();
+  HandleInterfaceDisconnection(
+      &commit_navigation_client_,
+      base::BindOnce(&NavigationRequest::OnRendererAbortedNavigation,
+                     base::Unretained(this)));
   return commit_navigation_client_.get();
 }