[Media Router] Convert MediaRouter to use GURL for presentation URLs.

content/public/browser/presentation_session.cc

 // 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.
 
 #include "content/public/browser/presentation_session.h"
 
 namespace content {
 
 PresentationSessionInfo::PresentationSessionInfo(
-    const std::string& presentation_url,
+    const GURL& presentation_url,
     const std::string& presentation_id)
-    : presentation_url(presentation_url),
-      presentation_id(presentation_id) {
-}
+    : presentation_url(presentation_url), presentation_id(presentation_id) {}
 
 PresentationSessionInfo::~PresentationSessionInfo() {
 }
 
 PresentationError::PresentationError(
     PresentationErrorType error_type,
     const std::string& message)
     : error_type(error_type),
       message(message) {
 }
 
 PresentationError::~PresentationError() {
 }
 
 }  // namespace content