(Set)IsOverridingUserAgent should be called on VisibleItem

ios/web/navigation/crw_session_controller.mm

Index: ios/web/navigation/crw_session_controller.mm
diff --git a/ios/web/navigation/crw_session_controller.mm b/ios/web/navigation/crw_session_controller.mm
index d03bf9481386425669ff7c8f9bbaf4f29a8a8796..2a50b724681b90b18abeca45267fc58bf690d200 100644
--- a/ios/web/navigation/crw_session_controller.mm
+++ b/ios/web/navigation/crw_session_controller.mm
@@ -496,10 +496,10 @@ - (void)pushNewItemWithURL:(const GURL&)URL
                 transition:(ui::PageTransition)transition {
   DCHECK(![self pendingEntry]);
   DCHECK([self currentEntry]);
-  web::NavigationItem* currentItem = [self currentEntry].navigationItem;
+  web::NavigationItem* visibleItem = [self visibleEntry].navigationItem;
   CHECK(web::history_state_util::IsHistoryStateChangeValid(
-      currentItem->GetURL(), URL));

[liaoyuke, 2017/02/22 00:12:32]

Confirmed with Kurt and it is safe to change all currentItem to visibleItem.

[Eugene But (OOO till 7-30), 2017/02/22 21:57:41]

Why is this visible? Should this be lastCommittedItem instead?

[kkhorimoto, 2017/02/22 22:54:15]

Since a page showing an interstitial can't do a pushState, we know that if both
the DCHECKs above pass, then the visible item is equal to the last committed
item.  I guess we should just use the lastCommittedItem here to avoid doing
unnecessary logic in GetVisibleItem.

[Eugene But (OOO till 7-30), 2017/02/23 00:54:23]

Yuke, please address this comment.

[Eugene But (OOO till 7-30), 2017/02/23 02:36:59]

Yuke?

[liaoyuke, 2017/02/23 17:50:42]

Sorry, missed this one. Done!

-  web::Referrer referrer(currentItem->GetURL(), web::ReferrerPolicyDefault);
+      visibleItem->GetURL(), URL));
+  web::Referrer referrer(visibleItem->GetURL(), web::ReferrerPolicyDefault);
 
   base::scoped_nsobject<CRWSessionEntry> pushedEntry([self
       sessionEntryWithURL:URL
@@ -508,7 +508,7 @@ - (void)pushNewItemWithURL:(const GURL&)URL
            initiationType:web::NavigationInitiationType::USER_INITIATED]);
 
   web::NavigationItemImpl* pushedItem = [pushedEntry navigationItemImpl];
-  pushedItem->SetIsOverridingUserAgent(currentItem->IsOverridingUserAgent());
+  pushedItem->SetIsOverridingUserAgent(visibleItem->IsOverridingUserAgent());
   pushedItem->SetSerializedStateObject(stateObject);
   pushedItem->SetIsCreatedFromPushState(true);
   web::SSLStatus& sslStatus = [self currentEntry].navigationItem->GetSSL();