Fix crash in StaticHTMLNativeContent when deallocating WKWebView on iOS9

ios/chrome/browser/ui/reading_list/offline_page_native_content.mm

Index: ios/chrome/browser/ui/reading_list/offline_page_native_content.mm
diff --git a/ios/chrome/browser/ui/reading_list/offline_page_native_content.mm b/ios/chrome/browser/ui/reading_list/offline_page_native_content.mm
index 7d1945ebd9585d5875e877c1ca11c733a5641880..95568e28a98f2580ec7ed0f22797a89f166a71e4 100644
--- a/ios/chrome/browser/ui/reading_list/offline_page_native_content.mm
+++ b/ios/chrome/browser/ui/reading_list/offline_page_native_content.mm
@@ -73,6 +73,7 @@
 
 - (void)willBeDismissed {
   [self restoreOnlineURL];
+  [super willBeDismissed];
 }
 
 - (void)close {
@@ -92,6 +93,9 @@
 - (void)restoreOnlineURL {
   web::NavigationItem* item =
       _webState->GetNavigationManager()->GetLastCommittedItem();
+  if (!item || item->GetVirtualURL() != [self virtualURL]) {

[Eugene But (OOO till 7-30), 2017/01/04 21:24:38]

Could you please add a comment which explains then this happens.

[Olivier, 2017/01/06 10:03:24]

This was possible in the dealloc.
Not true anymore.
I let a DCHECK to catch problem if we add calls to willBeDismissed.

+    return;
+  }
   item->SetURL([self virtualURL]);
   item->SetVirtualURL([self virtualURL]);
 }