[Media Router] Wiring for searching route providers for new sinks.

chrome/browser/media/router/media_router.mojom

Index: chrome/browser/media/router/media_router.mojom
diff --git a/chrome/browser/media/router/media_router.mojom b/chrome/browser/media/router/media_router.mojom
index 9a2f5e7e712f6fa1f0ef0764150f4f385d3a02b2..223ce0557ac3edf3565741aedcb12edfa4d481df 100644
--- a/chrome/browser/media/router/media_router.mojom
+++ b/chrome/browser/media/router/media_router.mojom
@@ -263,6 +263,10 @@ interface MediaRouteProvider {
   // |route_id| has been closed (via .close(), garbage collection or
   // navigation).
   DetachRoute(string route_id);
+
+  // Indicates that the Media Router is interested in finding a sink with id
+  // |sink_id| that is compatible with the source urn |media_source|.

[amp, 2016/03/16 17:20:12]

As mentioned on extension side, this makes more sense to me as search_criteria
rather than sink_id, but I may be misunderstanding how this is wired up.

[btolsch, 2016/03/16 18:36:30]

Done.

+  SearchProviders(string media_source, string sink_id);
 };
 
 // Interface for a service which observes state changes across media
@@ -304,6 +308,9 @@ interface MediaRouter {
   // Called when the Media Route Manager receives a new list of sinks.
   OnSinksReceived(string media_source, array<MediaSink> sinks);
 
+  // Called when the Media Route Manager receives a new list of sinks.

[amp, 2016/03/16 17:20:12]

Also as mentioned on the extension side change, this appears to be the same call
as OnSinksReceived above (in fact the comments are exactly the same).

I haven't followed through exactly why we would need a new method, there may be
a good reason I am missing.

[btolsch, 2016/03/16 18:36:30]

As mentioned on the extension side, OnSinksReceived is doing two things
differently than OnSearchSinksReceived:

1. OnSinksReceived is tracking media sources, not search criteria (here
sink_id).
2. OnSinksReceived is expecting a complete list of sinks that are compatible
with a media source but search is only providing additional sinks.

To make this work with a single function, search would have to send a complete
sink list and something other than a media source would have to be used as the
tracking key. I don't think we can overload the string to have both key
meanings, so maybe we could add an enum that indicates which type of key we're
using? This would also let us still only send search results as additions
instead of complete lists.

+  OnSearchSinksReceived(string sink_id, array<MediaSink> sinks);
+
   // Called when issues are reported for media routes.
   OnIssue(Issue issue);