Misc clean-up of TabCaptureApiTests; and re-enable more tests.

chrome/test/data/extensions/api_test/tab_capture/api_tests_audio.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 tabCapture = chrome.tabCapture;
-
-chrome.test.runTests([
-
-  function onlyAudio() {

[miu, 2014/11/19 01:15:54]

This moved into api_tests.js.

-    tabCapture.capture({audio: true}, function(stream) {
-      chrome.test.assertTrue(!!stream);
-      stream.stop();
-      chrome.test.succeed();
-    });
-  },
-
-  function invalidAudioConstraints() {

[miu, 2014/11/19 01:15:54]

This moved into constraints.js.

-    var tabCaptureListener = function(info) {
-      if (info.status == 'stopped') {
-        tabCapture.onStatusChanged.removeListener(tabCaptureListener);
-
-        tabCapture.capture({audio: true, video: true}, function(stream) {
-          chrome.test.assertTrue(!!stream);
-          chrome.test.succeed();
-        });
-      }
-    };
-    tabCapture.onStatusChanged.addListener(tabCaptureListener);
-
-    tabCapture.capture({audio: true,
-                        audioConstraints: {
-                          'mandatory': {
-                            'notValid': '123'
-                          }
-                        }}, function(stream) {
-                          chrome.test.assertTrue(!stream);
-                        });
-  }
-
-]);