GuestView: Move GuestViewManager extension dependencies to ExtensionsGuestViewManagerDelegate

extensions/browser/guest_view/guest_view_message_filter.cc

Index: extensions/browser/guest_view/guest_view_message_filter.cc
diff --git a/extensions/browser/guest_view/guest_view_message_filter.cc b/extensions/browser/guest_view/guest_view_message_filter.cc
index 3e833d56074f5e4458615c3c6431c993524cbcf7..26188fa74801cbdd468c52cc005bf2b6b7493096 100644
--- a/extensions/browser/guest_view/guest_view_message_filter.cc
+++ b/extensions/browser/guest_view/guest_view_message_filter.cc
@@ -65,8 +65,7 @@ void GuestViewMessageFilter::OnAttachGuest(
     int guest_instance_id,
     const base::DictionaryValue& params) {
   DCHECK_CURRENTLY_ON(BrowserThread::UI);
-  auto manager =
-      GuestViewManager::FromBrowserContextIfAvailable(browser_context_);
+  auto manager = GuestViewManager::FromBrowserContext(browser_context_);
   // We should have a GuestViewManager at this point. If we don't then the
   // embedder is misbehaving.
   if (!manager)