[Media Router] Use origin instead of URL for frame.

chrome/browser/media/router/presentation_request.h

 // Copyright 2015 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.
 
 #ifndef CHROME_BROWSER_MEDIA_ROUTER_PRESENTATION_REQUEST_H_
 #define CHROME_BROWSER_MEDIA_ROUTER_PRESENTATION_REQUEST_H_
 
 #include <string>
 #include <vector>
 
@@ skipping 26 matching lines @@
   const GURL& frame_url() const { return frame_url_; }
 
  private:
   // ID of RenderFrameHost that initiated the request.
   const RenderFrameHostId render_frame_host_id_;
 
   // URLs of presentation.
   const std::vector<GURL> presentation_urls_;
 
   // URL of frame from which the request was initiated.
+  // TODO(crbug.com/632623): Convert this to url::Origin as only the origin or
+  // hostname is used.
   const GURL frame_url_;
 };
 
 }  // namespace media_router
 
 #endif  // CHROME_BROWSER_MEDIA_ROUTER_PRESENTATION_REQUEST_H_