Remove swapped-out usage in --site-per-process.

content/renderer/history_entry.cc

Index: content/renderer/history_entry.cc
diff --git a/content/renderer/history_entry.cc b/content/renderer/history_entry.cc
index efd6fb54682e43d22d18aab7eaa5a9adcf0b9ead..c82056ba186f3efcedde4c969c8b9e0aea76963f 100644
--- a/content/renderer/history_entry.cc
+++ b/content/renderer/history_entry.cc
@@ -69,7 +69,7 @@ HistoryEntry::HistoryNode* HistoryEntry::HistoryNode::CloneAndReplace(
         item_.documentSequenceNumber());
   }
 
-  if (clone_children_of_target || !is_target_frame) {
+  if (current_frame && (clone_children_of_target || !is_target_frame)) {

[Charlie Reis, 2015/06/04 00:02:11]

Hmm.  I suppose this is needed for OOPIFs, but it doesn't really make sense.  I
guess we'll have to revisit this as well for the session history work, and not
just GoToEntry.  Maybe add a TODO to handle HistoryEntries in subframe
processes?

[nasko, 2015/06/04 14:57:13]

This is the one I wasn't really sure how it needs to be handled. If we don't
handle, we just crash, which isn't really good either :). It is my understanding
that most of this you are moving over to the browser process. Would that work
account for this case?
Added a TODO to ensure we keep track of this.

[Charlie Reis, 2015/06/04 22:27:31]

It's beyond what I've considered so far, but probably.  I've only gotten to the
GoToEntry stuff, but Blink still needs some notion of the current HistoryEntry,
so some of it is going to stick around.
Thanks.

[nasko, 2015/06/04 23:38:36]

Acknowledged.

     for (WebFrame* child = current_frame->GetWebFrame()->firstChild(); child;
          child = child->nextSibling()) {
       RenderFrameImpl* child_render_frame =