Implement native bindings for cast extensions API

chrome/renderer/resources/extensions/webrtc_cast_send_transport_custom_bindings.js

 // Copyright 2013 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.
 
 // Custom binding for the webrtc custom transport API.
 
 var binding = require('binding').Binding.create('webrtc.castSendTransport');
 var webrtc = requireNative('webrtc_natives');
 
 binding.registerCustomHook(function(bindingsAPI, extensionId) {
   var apiFunctions = bindingsAPI.apiFunctions;
 
   apiFunctions.setHandleRequest('create',

[scherkus (not reviewing), 2013/10/30 17:56:35]

kalman: are you saying that we should be doing argument validation here, meaning
the C++ code in webrtc_native_handler.cc is permitted to CHECK() fail as that
would indicate missing/incorrect validation here?

[not at google - send to devlin, 2013/10/30 18:13:48]

Actually it looks like validation does happen by default:

https://code.google.com/p/chromium/codesearch#chromium/src/chrome/renderer/re...

so you don't have to change this code, and you should CHECK in the C++.

-      function(track, innerTransportId, callback) {
-        webrtc.CreateCastSendTransport(track, innerTransportId, callback);
+      function(innerTransportId, track, callback) {
+        webrtc.CreateCastSendTransport(innerTransportId, track, callback);
   });
   apiFunctions.setHandleRequest('destroy',
       function(transportId) {
         webrtc.DestroyCastSendTransport(transportId);
   });
   apiFunctions.setHandleRequest('getCaps',
       function(transportId, callback) {
         webrtc.GetCapsCastSendTransport(transportId, callback);
   });
   apiFunctions.setHandleRequest('createParams',
       function(transportId, remoteCaps, callback) {
         webrtc.CreateParamsCastSendTransport(transportId, remoteCaps,
                                              callback);
   });
   apiFunctions.setHandleRequest('start',
       function(transportId, params) {
         webrtc.StartCastSendTransport(transportId, params);
   });
   apiFunctions.setHandleRequest('stop',
       function(transportId) {
         webrtc.StopCastSendTransport(transportId);
   });
 });
 
 exports.binding = binding.generate();