[Media Router] Add MediaSink subtypes

chrome/browser/media/router/mojo/media_router.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 media_router.mojom;
 
 import "mojo/common/time.mojom";
 import "url/mojo/origin.mojom";
+import "url/mojo/url.mojom";
 
 // Represents an output sink to which media can be routed.
 struct MediaSink {
   enum IconType {

[mark a. foltz, 2017/02/21 17:32:37]

Does this generated a nested class enum in the mojom.h? It would save some
typing to hoist this to the top level.  (Not to fix in this patch.)

[zhaobin, 2017/02/22 00:42:08]

Created crbug.com/694841.

     CAST,
     CAST_AUDIO,
     CAST_AUDIO_GROUP,
     GENERIC,
     HANGOUT
   };
 
   // The sink identifier, e.g. "rs71w7mFzYLFlabir_qO4NHl6SUc."
   string sink_id;
   // The human-readable name, e.g. "Janet's Chromecast".
   string name;
   // Optional description of the sink.
   string? description;
   // Optional domain of the sink if this sink is associated with an identity.
   string? domain;
   // The type of icon to show in the UI for this media sink.
   IconType icon_type;
 };
 
+// Represents a sink discovered by Media Router, which is pushed to the
+// MediaRouteProvider. It wraps a MediaSink with additional data required by the
+// MediaRouteProvider to perform additional operations, such as route creation.
+struct TypedMediaSink {

[mark a. foltz, 2017/02/17 02:22:31]

Does this need to be distinct from MediaSink?

If they were merged, we could typemap the combined MediaSink to a C++ object
MediaSinkInternal (replacing TypedMediaSink) and retain the MediaSink struct for
the public Media Router API.  This would reduce the amount of typemapping code
that needs to be maintained.

The downside is that cloud media sinks passed from MRP to the MR would not be
able to fill all the fields.  But it seems like you will need to handle that
case in the MR anyway.

WDYT? 

[imcheng, 2017/02/17 19:56:16]

It seems doing this will weaken the validation provided by Mojo, since we would
have to make all of these fields optional, in order to accommodate the
OnSinksReceived use case.

IMO, the extra type map for TypedMediaSink isn't too bad since it mostly reuses
the MediaSink typemap.

[mark a. foltz, 2017/02/21 17:32:37]

I see.  However we could move all the additional fields introduced in
TypedMediaSink to the type-specific structs.

CastMediaSink
  ip_address (is this needed since the MRP gets the cast channel id?)
  model_name (for feedback?)
  capabilities

DialMediaSink
  ip_address (is this needed since the MRP gets the app_url for launch/stop?)
  model_name (for feedback?)

CloudMediaSink
  domain

This way the same container struct is passed to/from the MRP through both APIs,
fewer typemaps are written, and each sink type defines exactly the fields it
needs (albeit with a couple of duplicates).  I feel this is conceptually cleaner
and less complex in the long run.




 

[zhaobin, 2017/02/22 00:42:08]

Done.

+  MediaSink sink;
+
+  string ip_address;
+
+  // Model name of the sink, if it represents a physical device.
+  string? model_name;
+
+  MediaSinkExtraData extra_data;
+};
+
+union MediaSinkExtraData {
+  DialMediaSink dial_media_sink;
+  CastMediaSink cast_media_sink;
+};
+
+struct DialMediaSink {
+  // Used for DIAL launch
+  url.mojom.Url app_url;
+};
+
+struct CastMediaSink {
+  int32 capabilities;

[mark a. foltz, 2017/02/17 02:22:31]

Can this be defined further?  What do the bit positions mean?

[zhaobin, 2017/02/22 00:42:08]

Done.

+
+  // ID of cast channel opened by Media Router. The ID can be
+  // used to send call chrome.cast.channel.send.
+  int32 cast_channel_id;
+};
+
 // Should be kept in sync with media_route.h.
 struct MediaRoute {
   // The ID of this media route, e.g. "r_PR1O_blkC9dsKp-tb1ti8qurOo".
   string media_route_id;
   // The ID of the media source being sent through this media route.
   // May be missing if route is not local.
   string? media_source;
   // The ID of sink that is rendering the media content.
   string media_sink_id;
   // Human readable description of this route, e.g.
@@ skipping 348 matching lines @@
 
   // Called when the a batch of messages arrives from the media sink for the
   // route given by |route_id|.
   // |StartListeningForRouteMessages| must be called first in order to receive
   // messages.
   // |route_id|: ID of route of the messages.
   // |messages|: A non-empty list of messages received.
   OnRouteMessagesReceived(string route_id,
                           array<RouteMessage> messages);
 };