[PresentationAPI] Implementing send() from WebPresentationClient to the 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;
 
 struct PresentationSessionInfo {
     string url;
     string id;
 };
 
 enum PresentationSessionState {
     CONNECTED,
     DISCONNECTED
 };
 
 enum PresentationErrorType {
     NO_AVAILABLE_SCREENS,
     SESSION_REQUEST_CANCELLED,
     NO_PRESENTATION_FOUND,
     UNKNOWN,
 };
 
 struct PresentationError {
     PresentationErrorType error_type;
     string message;
 };
 
 enum PresentationMessageType {
-   TEXT,
-   ARRAY_BUFFER,
+    TEXT,
+    ARRAY_BUFFER,
 };
 
 struct SessionMessage {
-   string presentation_url;
-   string presentation_id;
-   PresentationMessageType type;
-   string? message;
-   array<uint8>? data;
+    string presentation_url;
+    string presentation_id;
+    PresentationMessageType type;
+    string? message;
+    array<uint8>? data;
 };
 
 interface PresentationService {
     // Called when the frame sets or changes the default presentation URL or
     // presentation ID.
     SetDefaultPresentationURL(
         string default_presentation_url,
         string? default_presentation_id);
 
     // Returns the last screen availability state if it’s changed since the last
@@ skipping 30 matching lines @@
     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 send() is called by the frame. The true in the
+    // 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(SessionMessage message_request) => (bool success);
+
     // Called when closeSession() is called by the frame.
     CloseSession(string presentation_url, string presentation_id);
 
     // Called when the frame is ready to process the next state change. Returns
     // the last session state if it’s changed since the last time the callback
     // was called. Might cause the event fired with the initial state change.
     ListenForSessionStateChange()
         => (PresentationSessionInfo sessionInfo,
             PresentationSessionState newState);
 
     // Called when the frame is ready to process the next batch of messages.
     // When the callback carries null messages, there is an error
     // at the presentation service side.
     ListenForSessionMessages()
         => (array<SessionMessage>? messages);
 };