Add minimal implementation of unprefixed MediaSource API that has feature parity with prefixed API

LayoutTests/http/tests/media/media-source/mediasource-util.js

+(function(window) {
+    EventExpectationsManager = function(test) {
+        this.test_ = test;
+        this.eventTargetList_ = [];
+        this.waitCallbacks_ = [];
+    };
+
+    EventExpectationsManager.prototype.expectEvent = function(object, eventName, description)
+    {
+        var eventInfo = { 'target': object, 'type': eventName, 'description': description};
+        var expectations = this.getExpectations_(object);
+        expectations.push(eventInfo);
+
+        var t = this;
+        var waitHandler = this.test_.step_func(function() { t.handleWaitCallback_(); });
+        var eventHandler = this.test_.step_func(function(event)
+        {
+            object.removeEventListener(eventName, eventHandler);
+            var expected = expectations[0];
+            assert_equals(event.target, expected.target, "Event target match.");
+            assert_equals(event.type, expected.type, "Event types match.");
+            assert_equals(eventInfo.description, expected.description, "Descriptions match for '" +  event.type + "'.");
+
+            expectations.shift(1);
+            if (t.waitCallbacks_.length > 0)
+                setTimeout(waitHandler, 0);
+        });
+        object.addEventListener(eventName, eventHandler);
+    };
+
+    EventExpectationsManager.prototype.waitForExpectedEvents = function(callback)
+    {
+        this.waitCallbacks_.push(callback);
+        setTimeout(this.handleWaitCallback_.bind(this), 0);
+    };
+
+    EventExpectationsManager.prototype.expectingEvents = function()
+    {
+        for (var i = 0; i < this.eventTargetList_.length; ++i) {
+            if (this.eventTargetList_[i].expectations.length > 0) {
+                return true;
+            }
+        }
+        return false;
+    }
+
+    EventExpectationsManager.prototype.handleWaitCallback_ = function()
+    {
+        if (this.waitCallbacks_.length == 0 || this.expectingEvents())
+            return;
+        var callback = this.waitCallbacks_.shift(1);
+        callback();
+    };
+
+    EventExpectationsManager.prototype.getExpectations_ = function(target)
+    {
+        for (var i = 0; i < this.eventTargetList_.length; ++i) {
+            var info = this.eventTargetList_[i];
+            if (info.target == target) {
+                return info.expectations;
+            }
+        }
+        var expectations = [];
+        this.eventTargetList_.push({ 'target': target, 'expectations': expectations });
+        return expectations;
+    };
+
+    function loadData_(test, url, callback, isBinary)
+    {
+        var request = new XMLHttpRequest();
+        request.open("GET", url, true);
+        if (isBinary) {
+            request.responseType = 'arraybuffer';
+        }
+        request.onload = test.step_func(function(event)
+        {
+            if (request.status != 200) {
+                assert_unreached("Unexpected status code : " + request.status);
+                return;
+            }
+            var response = request.response;
+            if (isBinary) {
+                response = new Uint8Array(response);
+            }
+            callback(new Uint8Array(response));
+        });
+        request.onerror = test.step_func(function(event)
+        {
+            assert_unreached("Unexpected error");
+        });
+        request.send();
+    }
+
+    function openMediaSource_(test, mediaTag, callback)
+    {
+        var mediaSource = new MediaSource();
+        var mediaSourceURL = URL.createObjectURL(mediaSource);
+
+        var eventHandler = test.step_func(onSourceOpen);
+        function onSourceOpen(event)
+        {
+            mediaSource.removeEventListener('sourceopen', eventHandler);
+            URL.revokeObjectURL(mediaSourceURL);
+            callback(mediaSource);
+        }
+
+        mediaSource.addEventListener('sourceopen', eventHandler);
+        mediaTag.src = mediaSourceURL;
+    }
+
+    var MediaSourceUtil = {};
+
+    MediaSourceUtil.loadTextData = function(test, url, callback)
+    {
+        loadData_(test, url, callback, false);
+    };
+
+    MediaSourceUtil.loadBinaryData = function(test, url, callback)
+    {
+        loadData_(test, url, callback, true);
+    };
+
+    function getFirstSupportedType(typeList)
+    {
+        for (var i = 0; i < typeList.length; ++i) {
+            if (MediaSource.isTypeSupported(typeList[i]))
+                return typeList[i];
+        }
+        return "";
+    }
+
+    var audioOnlyTypes = ['audio/webm;codecs="vorbis"', 'audio/mp4;codecs="mp4a.40.2"'];
+    var videoOnlyTypes = ['video/webm;codecs="vp8"', 'video/mp4;codecs="avc1.4D4001"'];
+    var audioVideoTypes = ['video/webm;codecs="vp8,vorbis"', 'video/mp4;codecs="mp4a.40.2"'];
+    MediaSourceUtil.AUDIO_ONLY_TYPE = getFirstSupportedType(audioOnlyTypes);
+    MediaSourceUtil.VIDEO_ONLY_TYPE = getFirstSupportedType(videoOnlyTypes);
+    MediaSourceUtil.AUDIO_VIDEO_TYPE = getFirstSupportedType(audioVideoTypes);
+
+    function addExtraTestMethods(test)
+    {
+        test.failOnEvent = function(object, eventName)
+        {
+            object.addEventListener(eventName, test.step_func(function(event)
+            {
+                assert_unreached("Unexpected event '" + eventName + "'");
+            }));
+        };
+
+        test.endOnEvent = function(object, eventName)
+        {
+            object.addEventListener(eventName, test.step_func(function(event) { test.done(); }));
+        };
+
+        test.eventExpectations_ = new EventExpectationsManager(test);
+        test.expectEvent = function(object, eventName, description)
+        {
+            test.eventExpectations_.expectEvent(object, eventName, description);
+        };
+
+        test.waitForExpectedEvents = function(callback)
+        {
+            test.eventExpectations_.waitForExpectedEvents(callback);
+        };
+
+        var oldTestDone = test.done.bind(test);
+        test.done = function()
+        {
+            if (test.status == test.PASS)
+                assert_false(test.eventExpectations_.expectingEvents(), "No pending event expectations.");
+            oldTestDone();
+        };
+    };
+
+    window['MediaSourceUtil'] = MediaSourceUtil;
+    window['mediasource_test'] = function(testFunction, description)
+    {
+        return async_test(function(test) {
+            var mediaTag = document.createElement("video");
+            document.body.appendChild(mediaTag);
+
+            addExtraTestMethods(test);
+
+            // Overload done() so that element added to the document can be removed.
+            test.removeMediaElement_ = true;
+            var oldTestDone = test.done.bind(test);
+            test.done = function()
+            {
+                if (test.removeMediaElement_) {
+                    document.body.removeChild(mediaTag);
+                    test.removeMediaElement_ = false;
+                }
+                oldTestDone();
+            };
+
+            openMediaSource_(test, mediaTag, function(mediaSource)
+            {
+                testFunction(test, mediaTag, mediaSource);
+            });
+        }, description);
+
+    };
+})(window);