Cast: cast.streaming API to support null audio (or video) track

chrome/test/data/extensions/api_test/cast_streaming/null_stream.js

+// Copyright 2014 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.
+
+var rtpStream = chrome.cast.streaming.rtpStream;
+var tabCapture = chrome.tabCapture;
+var udpTransport = chrome.cast.streaming.udpTransport;
+var createSession = chrome.cast.streaming.session.create;
+var pass = chrome.test.callbackPass;
+
+chrome.test.runTests([
+  function noVideo() {
+    console.log("[TEST] noVideo");
+    chrome.tabs.create({"url": "about:blank"}, pass(function(tab) {
+      tabCapture.capture({audio: true, video: false},
+                         pass(function(stream) {
+        chrome.test.assertTrue(!!stream);
+        createSession(stream.getAudioTracks()[0],
+                      null,
+                      pass(function(stream, audioId, videoId, udpId) {
+          chrome.test.assertTrue(audioId > 0);
+          chrome.test.assertTrue(videoId == null);
+          chrome.test.assertTrue(udpId > 0);
+          rtpStream.destroy(audioId);
+          udpTransport.destroy(udpId);
+        }.bind(null, stream)));
+      }));
+    }));
+  },
+  function noAudio() {
+    console.log("[TEST] noAudio");
+    chrome.tabs.create({"url": "about:blank"}, pass(function(tab) {
+      tabCapture.capture({audio: false, video: true},
+                         pass(function(stream) {
+        chrome.test.assertTrue(!!stream);
+        createSession(null,
+                      stream.getVideoTracks()[0],
+                      pass(function(stream, audioId, videoId, udpId) {
+          chrome.test.assertTrue(audioId == null);
+          chrome.test.assertTrue(videoId > 0);
+          chrome.test.assertTrue(udpId > 0);
+          rtpStream.destroy(videoId);
+          udpTransport.destroy(udpId);
+        }.bind(null, stream)));
+      }));
+    }));
+  },
+  function noStream() {
+    console.log("[TEST] noAudio");
+    chrome.tabs.create({"url": "about:blank"}, pass(function(tab) {
+      try {
+        createSession(null, null, function(a, b, c) {});
+        chrome.test.fail();
+      } catch (e) {
+        // Success.
+      }
+    }));
+  },
+]);