[Media Router] 2nd take on fix route response callback lifetime in UI.

chrome/browser/media/router/create_session_request.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 "chrome/browser/media/router/create_session_request.h"
 
 #include "chrome/browser/media/router/media_source_helper.h"
 
 using content::PresentationSessionInfo;
 using content::PresentationError;
 
 namespace media_router {
 
 CreateSessionRequest::CreateSessionRequest(
     const std::string& presentation_url,
     const std::string& presentation_id,
     const GURL& frame_url,
     const PresentationSessionSuccessCallback& success_cb,
     const PresentationSessionErrorCallback& error_cb)
     : presentation_info_(presentation_url, presentation_id),
       media_source_(presentation_url),
       frame_url_(frame_url),
       success_cb_(success_cb),
       error_cb_(error_cb),
       cb_invoked_(false) {
 }
 
 CreateSessionRequest::~CreateSessionRequest() {
+  if (!cb_invoked_) {

[mark a. foltz, 2015/07/14 21:36:32]

Or just call MaybeInvokeErrorCallback()?

+    error_cb_.Run(content::PresentationError(
+        content::PRESENTATION_ERROR_UNKNOWN, "Unknown error."));
+  }
 }
 
 void CreateSessionRequest::MaybeInvokeSuccessCallback(
     const MediaRoute::Id& route_id) {
   if (!cb_invoked_) {
     // Overwrite presentation ID.
     success_cb_.Run(content::PresentationSessionInfo(
                         presentation_info_.presentation_url,
                         GetPresentationIdAndUrl(route_id).first),
                     route_id);
     cb_invoked_ = true;
   }
 }
 
 void CreateSessionRequest::MaybeInvokeErrorCallback(
     const content::PresentationError& error) {
   if (!cb_invoked_) {
     error_cb_.Run(error);
     cb_invoked_ = true;
   }
 }
 
 }  // namespace media_router