[Media Router] Connection state change listening redesign part 2.

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;
 
 struct PresentationSessionInfo {
   string url;
   string id;
 };
@@ skipping 72 matching lines @@
   // result callback notifies that the service is ready for next message.
   // The false in the result callback notifies the renderer to stop sending
   // the send requests and invalidate all pending requests. This occurs
   // for eg., when frame is deleted or navigated away.
   SendSessionMessage(PresentationSessionInfo sessionInfo,
                      SessionMessage message_request) => (bool success);
 
   // Called when closeSession() is called by the frame.
   CloseSession(string presentation_url, string presentation_id);
 
-  // Starts listening for state changes for sessions created on this frame.
-  // When state change occurs, PresentationServiceClient::OnSessionStateChanged
-  // will be invoked with the session and its new state.
-  // This is called after a presentation session is created.
-  ListenForSessionStateChange();
-
   // Starts listening for messages for session with |sessionInfo|.
   // Messages will be received in
   // PresentationServiceClient::OnSessionMessagesReceived.
   // This is called after a presentation session is created.
   ListenForSessionMessages(PresentationSessionInfo sessionInfo);
 };
 
 interface PresentationServiceClient {
   // Called when the client tries to listen for screen availability changes for
   // presentation of |url| but it is not supported by the device or underlying
   // platform. This can also be called if the device is currently in a mode
   // where it can't do screen discoveries (eg. low battery).
   OnScreenAvailabilityNotSupported(string url);
 
   // Called when the client is listening for screen availability for
   // presentation of |url| and the state changes. When the client starts to
   // listen for screen availability, this method will always be called to give
   // the current known state. It will then be called to notify of state updates.
   OnScreenAvailabilityUpdated(string url, bool available);
 
-  // See PresentationService::ListenForSessionStateChange.
-  OnSessionStateChanged(PresentationSessionInfo sessionInfo,
-                        PresentationConnectionState newState);
+  // Called when the state of PresentationConnection |connection| started on
+  // this frame has changed to |newState|.
+  OnConnectionStateChanged(PresentationSessionInfo connection,
+                           PresentationConnectionState newState);
 
   // See PresentationService::ListenForSessionMessages.
   OnSessionMessagesReceived(PresentationSessionInfo sessionInfo,
                             array<SessionMessage> messages);
 
   // See PresentationService::SetDefaultPresentationURL.
   OnDefaultSessionStarted(PresentationSessionInfo sessionInfo);
 };