Implementing closeSession from WebPresentationClient to PresentationService.

content/common/presentation/presentation_service.mojom

 // 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.
 
 module presentation;
 
 import "presentation_session.mojom";
 
 struct PresentationSessionInfo {
     PresentationSession session;
@@ skipping 53 matching lines @@
     // UA will generate the presentation id.
     StartSession(string presentation_url, string? presentation_id)
         => (PresentationSessionInfo? sessionInfo, PresentationError? error);
 
     // Called when joinSession() is called by the frame. The result callback
     // works the same as for the method above. JoinSession will join a known
     // session (i.e. when the page navigates or the user opens another tab)
     // silently and without user action.
     JoinSession(string presentation_url, string? presentation_id)
         => (PresentationSessionInfo? sessionInfo, PresentationError? error);
-};
+
+    // Called when closeSession() is called by the frame.
+    CloseSession(string presentation_url, string? presentation_id);

[whywhat, 2015/03/19 01:05:27]

I don't think the id is optional here. It will be either provided when calling
start/joinSession, or the UA will generate it. Did you intend to have a way to
close all sessions with the same URL? 

[haibinlu, 2015/03/19 01:15:37]

Right, it should not be optional. Updated. 

+};