Change ChooserController ownership model

components/chooser_controller/chooser_controller.cc

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "components/chooser_controller/chooser_controller.h"
 
 #include "content/public/browser/render_frame_host.h"
+#include "url/origin.h"
 
 ChooserController::ChooserController(content::RenderFrameHost* owner)
     : owning_frame_(owner) {}
 
 ChooserController::~ChooserController() {}
 
 url::Origin ChooserController::GetOrigin() const {
-  return const_cast<content::RenderFrameHost*>(owning_frame_)
-      ->GetLastCommittedOrigin();
+  return owning_frame_ ? owning_frame_->GetLastCommittedOrigin()
+                       : url::Origin();
 }