Skip self-referential frame checks for POST requests (Merge to M58).

content/browser/frame_host/navigation_handle_impl.cc

Index: content/browser/frame_host/navigation_handle_impl.cc
diff --git a/content/browser/frame_host/navigation_handle_impl.cc b/content/browser/frame_host/navigation_handle_impl.cc
index 380b80a125aa2b843387d6e2020c9d387171e864..4ebe13f190b6f137fe359df74015d9adc0872fcb 100644
--- a/content/browser/frame_host/navigation_handle_impl.cc
+++ b/content/browser/frame_host/navigation_handle_impl.cc
@@ -947,6 +947,12 @@ bool NavigationHandleImpl::IsSelfReferentialURL() {
   if (!is_renderer_initiated_)
     return false;
 
+  // Some sites rely on constructing frame hierarchies where frames are loaded
+  // via POSTs with the same URLs, so exempt POST requests.  See
+  // https://crbug.com/710008.
+  if (method_ == "POST")
+    return false;
+
   // We allow one level of self-reference because some sites depend on that,
   // but we don't allow more than one.
   bool found_self_reference = false;