Make tab capture media stream requests verify that the request came from extension API

chrome/test/data/extensions/api_test/tab_capture/permissions/test.js

+// Copyright (c) 2012 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 tabCapture = chrome.tabCapture;
+
+chrome.test.runTests([
+
+  function cannotDirectlyUseGetUserMedia() {
+    var failure = function() {
+      chrome.test.succeed();
+    };
+
+    var success = function(stream) {
+      chrome.test.fail();
+    };
+
+    navigator.webkitGetUserMedia({
+      video: {
+        mandatory: { chromeMediaSource: 'tab', chromeMediaSourceId: '1:2' },
+      },
+      audio: {
+        mandatory: { chromeMediaSource: 'tab', chromeMediaSourceId: '1:2' },
+      }
+    }, success, failure);
+  },
+
+]);