[Media Router] Custom Controls 2 - add MediaRouter::GetRouteController()

chrome/browser/media/router/mojo/media_router.mojom

Index: chrome/browser/media/router/mojo/media_router.mojom
diff --git a/chrome/browser/media/router/mojo/media_router.mojom b/chrome/browser/media/router/mojo/media_router.mojom
index 173de06877a7f630daee0c4f115351fdfa3318d7..1dcce2f3f86e821b29a0bf7b7127b82e2f664ca0 100644
--- a/chrome/browser/media/router/mojo/media_router.mojom
+++ b/chrome/browser/media/router/mojo/media_router.mojom
@@ -4,6 +4,8 @@
 
 module media_router.mojom;
 
+import "chrome/browser/media/router/mojo/media_controller.mojom";
+import "chrome/browser/media/router/mojo/media_status.mojom";
 import "mojo/common/time.mojom";
 import "net/interfaces/ip_address.mojom";
 import "url/mojo/origin.mojom";
@@ -79,8 +81,7 @@ struct MediaRoute {
   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.
-  // "Tab casting".
+  // Human readable description of this route, e.g. "Tab casting".
   string description;
   // Specifies that the route is requested locally.
   bool is_local;
@@ -363,6 +364,24 @@ interface MediaRouteProvider {
               string media_source,
               SinkSearchCriteria search_criteria) =>
                   (string sink_id);
+
+  // Creates a controller for the media route with given |route_id| and binds it
+  // to |media_controller| for receiving media commands. This method returns
+  // false if such a media route doesn't exist, a controller already exists
+  // for it, or there was an error while creating a controller.

[mark a. foltz, 2017/03/30 23:03:28]

I think an earlier draft returned an existing controller if it already exists. 
Is it possible to do that here?  Otherwise this is a little fragile - only the
code that owns the previously-created controller can call it safely.  

Since I'm pretty sure only the MR is ever going to call this code (and it owns
the map of routes to controllers) not a big deal.  More of a general API design
bikeshed.

[imcheng, 2017/03/31 01:30:25]

We can bind multiple interface requests to the same controller instance in the
component, if we need to do this in the future. For now, it is slight simpler if
we can assume if there can only be one binding per controller.

+  // |media_controller| becomes invalid when the media route is terminated. The
+  // created controller is destroyed when |media_controller| becomes invalid.

[mark a. foltz, 2017/03/30 23:03:28]

If a returned controller is invalidated/destroyed, can this method be called
again on the same route id to create a new one?  Please clarify comment above.

[takumif, 2017/04/04 03:19:50]

Done.

+  // TODO(takumif): Consider returning an enum instead of a bool to distinguish
+  // between error conditions for metrics/debugging.
+  CreateMediaRouteController(string route_id,
+                             MediaController& media_controller) =>
+                                 (bool success);
+
+  // Sets the observer to be notified whenever there is a change in the status
+  // of a media route. A media route can have at most one observer at a time,
+  // and it will be overwritten each time this method is called with the same
+  // |route_id|.
+  SetMediaRouteStatusObserver(string route_id, MediaStatusObserver observer);
 };
 
 // Interface for a service which observes state changes across media