Revert "Introduce AncestorThrottle, which will process 'X-Frame-Options' headers."

content/browser/loader/navigation_resource_throttle.cc

Index: content/browser/loader/navigation_resource_throttle.cc
diff --git a/content/browser/loader/navigation_resource_throttle.cc b/content/browser/loader/navigation_resource_throttle.cc
index b7d91f0498ac125de16b24a4b936d765629980ed..3c0f5121c4c188e3b599069b6e1cd0877d8d01b7 100644
--- a/content/browser/loader/navigation_resource_throttle.cc
+++ b/content/browser/loader/navigation_resource_throttle.cc
@@ -259,16 +259,6 @@ void NavigationResourceThrottle::OnUIChecksPerformed(
     controller()->CancelAndIgnore();
   } else if (result == NavigationThrottle::CANCEL) {
     controller()->Cancel();
-  } else if (result == NavigationThrottle::BLOCK_RESPONSE) {
-    // TODO(mkwst): If we cancel the main frame request with anything other than
-    // 'net::ERR_ABORTED', we'll trigger some special behavior that might not be
-    // desirable here (non-POSTs will reload the page, while POST has some logic
-    // around reloading to avoid duplicating actions server-side). For the
-    // moment, only child frame navigations should be blocked. If we need to
-    // block main frame navigations in the future, we'll need to carefully
-    // consider the right thing to do here.
-    DCHECK(!ResourceRequestInfo::ForRequest(request_)->IsMainFrame());
-    controller()->CancelWithError(net::ERR_BLOCKED_BY_RESPONSE);
   } else {
     controller()->Resume();
   }