Ensure the NavigationHandle's nav entry ID is updated during transfers.

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 e24b58e84c6d09a62902022699c380921c95f04c..f1f0d2564b0b4e82afe1a87da1e62fa81d800fb3 100644
--- a/content/browser/frame_host/navigation_controller_impl.cc
+++ b/content/browser/frame_host/navigation_controller_impl.cc
@@ -854,19 +854,24 @@ bool NavigationControllerImpl::RendererDidNavigate(
       pending_entry_->restore_type() != NavigationEntryImpl::RESTORE_NONE)
     pending_entry_->set_restore_type(NavigationEntryImpl::RESTORE_NONE);
 
-  // If we are doing a cross-site reload, we need to replace the existing
-  // navigation entry, not add another entry to the history. This has the side
-  // effect of removing forward browsing history, if such existed. Or if we are
-  // doing a cross-site redirect navigation, we will do a similar thing.
+  // If the pending entry matches this commit, check if it says to replace the
+  // current entry (which preserves forward history).  This is used for things
+  // like cross-process client redirects or cross-process reloads.

[Charlie Harrison, 2016/03/11 15:15:14]

Maybe reference location.replace(<cross-site>). I was initially confused reading
this comment about why you would ever need a cross-process reload.

[Charlie Reis, 2016/03/11 20:12:48]

Done.

   //
   // If this is an error load, we may have already removed the pending entry
   // when we got the notice of the load failure. If so, look at the copy of the
-  // pending parameters that were saved.
-  if (params.url_is_unreachable && failed_pending_entry_id_ != 0) {
+  // pending parameters that were saved and see if they match the handle.
+  NavigationHandleImpl* handle = rfh->navigation_handle();
+  DCHECK(handle);
+  if (params.url_is_unreachable && failed_pending_entry_id_ != 0 &&
+      handle->pending_nav_entry_id() == failed_pending_entry_id_) {
     details->did_replace_entry = failed_pending_entry_should_replace_;
+  } else if (pending_entry_ &&
+             pending_entry_->GetUniqueID() == handle->pending_nav_entry_id() &&

[Charlie Harrison, 2016/03/11 15:15:14]

Suggestion: This logic is duplicated in a bunch of places. It might be nice to
consolidate it. I'm mainly thinking of the check in
|RendererDidNavigateToNewPage|. Up to you though, it's arguably less clean to
thread a bool through that function.

[Charlie Reis, 2016/03/11 20:12:48]

Good idea.  I wrote a helper function for it.

We can now be sure that the handle isn't null in the
RendererDidNavigateToNewPage case as well, thanks to the unit test changes.

+             pending_entry_->should_replace_entry()) {
+    details->did_replace_entry = pending_entry_->should_replace_entry();
   } else {
-    details->did_replace_entry = pending_entry_ &&
-                                 pending_entry_->should_replace_entry();
+    details->did_replace_entry = false;
   }
 
   // Do navigation-type specific actions. These will make and commit an entry.