MimeHandlerViewGuest: Ignore title changes due to navigations.

extensions/browser/guest_view/mime_handler_view/mime_handler_view_guest.cc

Index: extensions/browser/guest_view/mime_handler_view/mime_handler_view_guest.cc
diff --git a/extensions/browser/guest_view/mime_handler_view/mime_handler_view_guest.cc b/extensions/browser/guest_view/mime_handler_view/mime_handler_view_guest.cc
index 55b2426eab7da641a14c52ae87de91e380525b9a..1f9ebfbb7b7acc4bc814c2ec972acbb81bdd7e2a 100644
--- a/extensions/browser/guest_view/mime_handler_view/mime_handler_view_guest.cc
+++ b/extensions/browser/guest_view/mime_handler_view/mime_handler_view_guest.cc
@@ -169,6 +169,11 @@ void MimeHandlerViewGuest::NavigationStateChanged(
   if (!(changed_flags & content::INVALIDATE_TYPE_TITLE))
     return;
 
+  // Only consider title changes not triggered by URL changes. Otherwise, the
+  // URL of the mime handler will be displayed.
+  if (changed_flags & content::INVALIDATE_TYPE_URL)
+    return;
+
   if (!is_full_page_plugin())
     return;