Fix null check to avoid RendererDidNavigateSamePage crash.

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 e49372f1eaa7a76db3cd551e03ea13a037c56f2c..ba6b142f6ea5ada6ac70a0bb602386c797155f2d 100644
--- a/content/browser/frame_host/navigation_controller_impl.cc
+++ b/content/browser/frame_host/navigation_controller_impl.cc
@@ -1008,7 +1008,7 @@ NavigationType NavigationControllerImpl::ClassifyNavigation(
     // make sure Blink didn't treat a new cross-process navigation as inert, and
     // thus set params.did_create_new_entry to false. In that case, we must
     // treat it as NEW since the SiteInstance doesn't match the entry.
-    if (GetLastCommittedEntry() &&
+    if (!GetLastCommittedEntry() ||
         GetLastCommittedEntry()->site_instance() != rfh->GetSiteInstance())
       return NAVIGATION_TYPE_NEW_PAGE;