Don't update subframes on parent frame commits.

content/browser/frame_host/navigation_controller_impl.cc

Index: content/browser/frame_host/navigation_controller_impl.cc
diff --git a/content/browser/frame_host/navigation_controller_impl.cc b/content/browser/frame_host/navigation_controller_impl.cc
index 7446d5153b845270ae510ff358d4c2fb960cf9e4..b3f98f369e9f34cc73f034a0d98a7da40b1602a0 100644
--- a/content/browser/frame_host/navigation_controller_impl.cc
+++ b/content/browser/frame_host/navigation_controller_impl.cc
@@ -1878,6 +1878,19 @@ void NavigationControllerImpl::FindFramesToNavigate(
         new_item->document_sequence_number() ==
             old_item->document_sequence_number()) {
       same_document_loads->push_back(std::make_pair(frame, new_item));
+      // This is a bug; we should not return here. Rather, we should continue on

[Charlie Reis, 2016/05/05 17:45:42]

nit: Blank line before, and start with TODO(avi, creis).  (It's not necessarily
something you personally have to fix, but you're knowledgable about it.)

[Avi (use Gerrit), 2016/05/05 19:06:21]

Done.

+      // and navigate all child frames which have also changed. This bug is the
+      // cause of <https://crbug.com/542299>.
+      //
+      // However, this bug masks a deeper and worse problem. Doing a pushState
+      // immediately after loading a subframe is a race, one that no web page
+      // author expects. If we fix this bug, many large websites break. For
+      // example, see <https://crbug.com/598043> and the spec discussion at

[Charlie Reis, 2016/05/05 17:45:42]

Let's also mention 600534.

[Avi (use Gerrit), 2016/05/05 19:06:21]

That's a Google-only bug; do we want to mention it?

[Charlie Reis, 2016/05/05 19:34:22]

Ah.  No, just listing it in the CL description should be sufficient then.

+      // <https://github.com/whatwg/html/issues/1191>.
+      //
+      // For now, we accept this bug, and hope to resolve the race in a
+      // different way that will one day allow us to fix this.
+      return;
     } else {
       different_document_loads->push_back(std::make_pair(frame, new_item));
       // For a different document, the subframes will be destroyed, so there's