(Re-)introduce AncestorThrottle to handle 'X-Frame-Options'.

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 4c24485495582a9779114f52df872e9a33ff8b8c..157cb4d92a690c59af29ca25749de5ff8890677b 100644
--- a/content/browser/frame_host/navigation_request.cc
+++ b/content/browser/frame_host/navigation_request.cc
@@ -446,7 +446,7 @@ void NavigationRequest::OnResponseStarted(
 
 void NavigationRequest::OnRequestFailed(bool has_stale_copy_in_cache,
                                         int net_error) {
-  DCHECK(state_ == STARTED);
+  DCHECK(state_ == STARTED || state_ == RESPONSE_STARTED);
   state_ = FAILED;
   navigation_handle_->set_net_error_code(static_cast<net::Error>(net_error));
   frame_tree_node_->navigator()->FailedNavigation(
@@ -467,6 +467,7 @@ void NavigationRequest::OnRequestStarted(base::TimeTicks timestamp) {
 void NavigationRequest::OnStartChecksComplete(
     NavigationThrottle::ThrottleCheckResult result) {
   CHECK(result != NavigationThrottle::DEFER);
+  CHECK(result != NavigationThrottle::BLOCK_RESPONSE);
 
   // Abort the request if needed. This will destroy the NavigationRequest.
   if (result == NavigationThrottle::CANCEL_AND_IGNORE ||
@@ -551,6 +552,7 @@ void NavigationRequest::OnStartChecksComplete(
 void NavigationRequest::OnRedirectChecksComplete(
     NavigationThrottle::ThrottleCheckResult result) {
   CHECK(result != NavigationThrottle::DEFER);
+  CHECK(result != NavigationThrottle::BLOCK_RESPONSE);
 
   // Abort the request if needed. This will destroy the NavigationRequest.
   if (result == NavigationThrottle::CANCEL_AND_IGNORE ||
@@ -575,6 +577,11 @@ void NavigationRequest::OnWillProcessResponseChecksComplete(
     return;
   }
 
+  if (result == NavigationThrottle::BLOCK_RESPONSE) {
+    OnRequestFailed(false, net::ERR_BLOCKED_BY_RESPONSE);
+    return;
+  }
+
   // Have the processing of the response resume in the network stack.
   loader_->ProceedWithResponse();