Implement support for <extensionoptions> embedding in WebUI

chrome/browser/extensions/api/guest_view/guest_view_internal_api.cc

Index: chrome/browser/extensions/api/guest_view/guest_view_internal_api.cc
diff --git a/chrome/browser/extensions/api/guest_view/guest_view_internal_api.cc b/chrome/browser/extensions/api/guest_view/guest_view_internal_api.cc
index cc2ac3b88617616dd0acc0f5222f6162c6fe85ba..5642bcb703e2133f542e7ddfd1918512982c92e4 100644
--- a/chrome/browser/extensions/api/guest_view/guest_view_internal_api.cc
+++ b/chrome/browser/extensions/api/guest_view/guest_view_internal_api.cc
@@ -33,8 +33,16 @@ bool GuestViewInternalCreateGuestFunction::RunAsync() {
   GuestViewManager::WebContentsCreatedCallback callback =
       base::Bind(&GuestViewInternalCreateGuestFunction::CreateGuestCallback,
                  this);
+
+  // If this the guest is an <extensionoptions> to be embedded in a WebUI, then
+  // there is no extension, and extension() will be null. Use an empty string
+  // instead.
+  std::string embedder_extension_id;
+  if (extension())
+    embedder_extension_id = extension_id();
+
   guest_view_manager->CreateGuest(view_type,
-                                  extension_id(),
+                                  embedder_extension_id,
                                   GetAssociatedWebContents(),
                                   *create_params,
                                   callback);