GuestView: Move lifetime management out of content

extensions/browser/guest_view/app_view/app_view_guest.cc

Index: extensions/browser/guest_view/app_view/app_view_guest.cc
diff --git a/extensions/browser/guest_view/app_view/app_view_guest.cc b/extensions/browser/guest_view/app_view/app_view_guest.cc
index e608a4904ff206ea775acb74c6cdf8c17c57afd1..92608ace93ec33f3290d780c4e95e26305e1e30a 100644
--- a/extensions/browser/guest_view/app_view/app_view_guest.cc
+++ b/extensions/browser/guest_view/app_view/app_view_guest.cc
@@ -203,8 +203,12 @@ void AppViewGuest::DidAttachToEmbedder() {
   // element. This means that the host element knows how to route input
   // events to the guest, and the guest knows how to get frames to the
   // embedder.
+  if (!url_.is_valid())
+    return;
+
   web_contents()->GetController().LoadURL(
       url_, content::Referrer(), ui::PAGE_TRANSITION_LINK, std::string());
+  url_ = GURL();
 }
 
 void AppViewGuest::DidInitialize() {