new file mode 100644
--- /dev/null
+++ b/dom/media/test/eme.js
@@ -0,0 +1,174 @@
+const KEYSYSTEM_TYPE = "org.w3.clearkey";
+
+function bail(message)
+{
+  return function(err) {
+    ok(false, message);
+    if (err) {
+      info(err);
+    }
+    SimpleTest.finish();
+  }
+}
+
+function ArrayBufferToString(arr)
+{
+  var str = '';
+  var view = new Uint8Array(arr);
+  for (var i = 0; i < view.length; i++) {
+    str += String.fromCharCode(view[i]);
+  }
+  return str;
+}
+
+function StringToArrayBuffer(str)
+{
+  var arr = new ArrayBuffer(str.length);
+  var view = new Uint8Array(arr);
+  for (var i = 0; i < str.length; i++) {
+    view[i] = str.charCodeAt(i);
+  }
+  return arr;
+}
+
+function Base64ToHex(str)
+{
+  var bin = window.atob(str.replace(/-/g, "+").replace(/_/g, "/"));
+  var res = "";
+  for (var i = 0; i < bin.length; i++) {
+    res += ("0" + bin.charCodeAt(i).toString(16)).substr(-2);
+  }
+  return res;
+}
+
+function HexToBase64(hex)
+{
+  var bin = "";
+  for (var i = 0; i < hex.length; i += 2) {
+    bin += String.fromCharCode(parseInt(hex.substr(i, 2), 16));
+  }
+  return window.btoa(bin).replace(/=/g, "").replace(/\+/g, "-").replace(/\//g, "_");
+}
+
+function UpdateSessionFunc(test) {
+  return function(ev) {
+    var msgStr = ArrayBufferToString(ev.message);
+    var msg = JSON.parse(msgStr);
+
+    info("got message from CDM: " + msgStr);
+    is(msg.type, test.sessionType, "Key session type should match");
+    ok(msg.kids, "message event should contain key ID array");
+
+    var outKeys = [];
+
+    for (var i = 0; i < msg.kids.length; i++) {
+      var id64 = msg.kids[i];
+      var idHex = Base64ToHex(msg.kids[i]).toLowerCase();
+      var key = test.keys[idHex];
+
+      if (key) {
+        info("found key " + key + " for key id " + idHex);
+        outKeys.push({
+          "kty":"oct",
+          "alg":"A128KW",
+          "kid":id64,
+          "k":HexToBase64(key)
+        });
+      } else {
+        bail("Couldn't find key for key id " + idHex);
+      }
+    }
+
+    var update = JSON.stringify({
+      "keys" : outKeys,
+      "type" : msg.type
+    });
+    info("sending update message to CDM: " + update);
+
+    ev.target.update(StringToArrayBuffer(update)).then(function() {
+      info("MediaKeySession update ok!");
+    }, bail("MediaKeySession update failed"));
+  }
+}
+
+function PlayFragmented(test, elem)
+{
+  return new Promise(function(resolve, reject) {
+    var ms = new MediaSource();
+    elem.src = URL.createObjectURL(ms);
+
+    var sb;
+    var curFragment = 0;
+
+    function addNextFragment() {
+      if (curFragment >= test.fragments.length) {
+        ms.endOfStream();
+        resolve();
+        return;
+      }
+
+      var fragmentFile = test.fragments[curFragment++];
+
+      var req = new XMLHttpRequest();
+      req.open("GET", fragmentFile);
+      req.responseType = "arraybuffer";
+
+      req.addEventListener("load", function() {
+        sb.appendBuffer(new Uint8Array(req.response));
+      });
+
+      info("fetching resource " + fragmentFile);
+      req.send(null);
+    }
+
+    ms.addEventListener("sourceopen", function () {
+      sb = ms.addSourceBuffer(test.type);
+      sb.addEventListener("updateend", addNextFragment);
+
+      addNextFragment();
+    })
+  });
+}
+
+// Returns a promise that is resovled when the media element is ready to have
+// its play() function called; when it's loaded MSE fragments, or once the load
+// has started for non-MSE video.
+function LoadTest(test, elem)
+{
+  if (test.fragments) {
+    return PlayFragmented(test, elem);
+  }
+
+  // This file isn't fragmented; set the media source normally.
+  return new Promise(function(resolve, reject) {
+    elem.src = test.name;
+    resolve();
+  });
+}
+
+function SetupEME(test, token, params)
+{
+  var v = document.createElement("video");
+
+  v.addEventListener("encrypted", function(ev) {
+    info(token + " got encrypted event");
+    MediaKeys.create(KEYSYSTEM_TYPE).then(function(mediaKeys) {
+      info(token + " created MediaKeys object ok");
+      mediaKeys.sessions = [];
+      return v.setMediaKeys(mediaKeys);
+    }, bail("failed to create MediaKeys object")).then(function() {
+      info(token + " set MediaKeys on <video> element ok");
+
+      var session = v.mediaKeys.createSession(test.sessionType);
+      if (params && params.onsessioncreated) {
+        params.onsessioncreated(session);
+      }
+      session.addEventListener("message", UpdateSessionFunc(test));
+      session.generateRequest(ev.initDataType, ev.initData).then(function() {
+      }, bail(token + " Failed to initialise MediaKeySession"));
+
+    }, bail(token + " Failed to set MediaKeys on <video> element"));
+  });
+
+  return v;
+}

--- a/dom/media/test/mochitest.ini
+++ b/dom/media/test/mochitest.ini
@@ -135,16 +135,17 @@ support-files =
   detodos.opus
   detodos.opus^headers^
   detodos.webm
   detodos.webm^headers^
   dirac.ogg
   dirac.ogg^headers^
   dynamic_redirect.sjs
   dynamic_resource.sjs
+  eme.js
   gizmo-frag-cenc1.m4s
   gizmo-frag-cenc2.m4s
   gizmo-frag-cencinit.mp4
   file_access_controls.html
   fragment_noplay.js
   fragment_play.js
   gizmo.mp4
   gizmo.mp4^headers^

--- a/dom/media/test/test_encryptedMediaExtensions.html
+++ b/dom/media/test/test_encryptedMediaExtensions.html
@@ -1,162 +1,22 @@
 <!DOCTYPE HTML>
 <html>
 <head>
   <title>Test Encrypted Media Extensions</title>
   <script type="text/javascript" src="/tests/SimpleTest/SimpleTest.js"></script>
   <link rel="stylesheet" type="text/css" href="/tests/SimpleTest/test.css" />
   <script type="text/javascript" src="manifest.js"></script>
+  <script type="text/javascript" src="eme.js"></script>
 </head>
 <body>
 <pre id="test">
 <script class="testbody" type="text/javascript">
 var manager = new MediaTestManager;
 
-const KEYSYSTEM_TYPE = "org.w3.clearkey";
-
-function bail(message)
-{
-  return function(err) {
-    ok(false, message);
-    if (err) {
-      info(err);
-    }
-    SimpleTest.finish();
-  }
-}
-
-function ArrayBufferToString(arr)
-{
-  var str = '';
-  var view = new Uint8Array(arr);
-  for (var i = 0; i < view.length; i++) {
-    str += String.fromCharCode(view[i]);
-  }
-  return str;
-}
-
-function StringToArrayBuffer(str)
-{
-  var arr = new ArrayBuffer(str.length);
-  var view = new Uint8Array(arr);
-  for (var i = 0; i < str.length; i++) {
-    view[i] = str.charCodeAt(i);
-  }
-  return arr;
-}
-
-function Base64ToHex(str)
-{
-  var bin = window.atob(str.replace(/-/g, "+").replace(/_/g, "/"));
-  var res = "";
-  for (var i = 0; i < bin.length; i++) {
-    res += ("0" + bin.charCodeAt(i).toString(16)).substr(-2);
-  }
-  return res;
-}
-
-function HexToBase64(hex)
-{
-  var bin = "";
-  for (var i = 0; i < hex.length; i += 2) {
-    bin += String.fromCharCode(parseInt(hex.substr(i, 2), 16));
-  }
-  return window.btoa(bin).replace(/=/g, "").replace(/\+/g, "-").replace(/\//g, "_");
-}
-
-function UpdateSessionFunc(test) {
-  return function(ev) {
-    var msgStr = ArrayBufferToString(ev.message);
-    var msg = JSON.parse(msgStr);
-
-    info("got message from CDM: " + msgStr);
-    is(msg.type, test.sessionType, "Key session type should match");
-    ok(msg.kids, "message event should contain key ID array");
-
-    var outKeys = [];
-
-    for (var i = 0; i < msg.kids.length; i++) {
-      var id64 = msg.kids[i];
-      var idHex = Base64ToHex(msg.kids[i]).toLowerCase();
-      var key = test.keys[idHex];
-
-      if (key) {
-        info("found key " + key + " for key id " + idHex);
-        outKeys.push({
-          "kty":"oct",
-          "alg":"A128KW",
-          "kid":id64,
-          "k":HexToBase64(key)
-        });
-      } else {
-        bail("Couldn't find key for key id " + idHex);
-      }
-    }
-
-    var update = JSON.stringify({
-      "keys" : outKeys,
-      "type" : msg.type
-    });
-    info("sending update message to CDM: " + update);
-
-    ev.target.update(StringToArrayBuffer(update)).then(function() {
-      info("MediaKeySession update ok!");
-    }, bail("MediaKeySession update failed"));
-  }
-}
-
-function PlayFragmented(test, elem)
-{
-  var ms = new MediaSource();
-  elem.src = URL.createObjectURL(ms);
-
-  var sb;
-  var curFragment = 0;
-
-  function addNextFragment() {
-    if (curFragment >= test.fragments.length) {
-      ms.endOfStream();
-      elem.play();
-      return;
-    }
-
-    var fragmentFile = test.fragments[curFragment++];
-
-    var req = new XMLHttpRequest();
-    req.open("GET", fragmentFile);
-    req.responseType = "arraybuffer";
-
-    req.addEventListener("load", function() {
-      sb.appendBuffer(new Uint8Array(req.response));
-    });
-
-    info("fetching resource " + fragmentFile);
-    req.send(null);
-  }
-
-  ms.addEventListener("sourceopen", function () {
-    sb = ms.addSourceBuffer(test.type);
-    sb.addEventListener("updateend", addNextFragment);
-
-    addNextFragment();
-  });
-}
-
-function PlayTest(test, elem)
-{
-  if (test.fragments) {
-    PlayFragmented(test, elem);
-    return;
-  }
-
-  // This file isn't fragmented; set the media source normally.
-  elem.src = test.name;
-  elem.play();
-}
 
 function KeysChangeFunc(session, keys) {
   session.keyIdsReceived = [];
   for (var keyid in keys) {
     info("Set " + keyid + " to false in session.keyIdsReceived");
     session.keyIdsReceived[keyid] = false;
   }
   return function(ev) {
@@ -171,76 +31,66 @@ function KeysChangeFunc(session, keys) {
     }, bail("Failed to get keyIds"));
   }
 }
 
 function startTest(test, token)
 {
   manager.started(test._token);
 
-  var v = document.createElement("video");
+  var sessions = [];
+
+  var v = SetupEME(test, token,
+    {
+      onsessioncreated: function(session) {
+        sessions.push(session);
+        session.addEventListener("keyschange", KeysChangeFunc(session, test.keys), false);
+      }
+    }
+  );
+  
   var gotEncrypted = false;
   var gotPlaying = false;
 
   v.addEventListener("encrypted", function(ev) {
-    gotEncrypted = true;
-
-    info(token + " got encrypted event");
     ok(MediaKeys.isTypeSupported(KEYSYSTEM_TYPE, ev.initDataType, test.type),
        token + " MediaKeys should support this keysystem");
-
-    MediaKeys.create(KEYSYSTEM_TYPE).then(function(mediaKeys) {
-      info(token + " created MediaKeys object ok");
-      mediaKeys.sessions = [];
-      return v.setMediaKeys(mediaKeys);
-    }, bail("failed to create MediaKeys object")).then(function() {
-      info(token + " set MediaKeys on <video> element ok");
-
-      ok(MediaKeys.isTypeSupported(KEYSYSTEM_TYPE, ev.initDataType, test.type),
-         "MediaKeys should still support keysystem after CDM created...");
-
-      var session = v.mediaKeys.createSession(test.sessionType);
-      v.mediaKeys.sessions.push(session);
-      session.addEventListener("keyschange", KeysChangeFunc(session, test.keys), false);
-      session.addEventListener("message", UpdateSessionFunc(test));
-      session.generateRequest(ev.initDataType, ev.initData).then(function() {
-      }, bail(token + " Failed to initialise MediaKeySession"));
-
-    }, bail(token + " Failed to set MediaKeys on <video> element"));
+    gotEncrypted = true;
   });
 
   v.addEventListener("playing", function () { gotPlaying = true; });
 
   v.addEventListener("ended", function(ev) {
     ok(true, token + " got ended event");
     manager.finished(test._token);
 
     ok(gotEncrypted, token + " encrypted event should have fired");
     ok(gotPlaying, token + " playing event should have fired");
 
     ok(Math.abs(test.duration - v.duration) < 0.1,
        token + " Duration of video should be corrrect");
     ok(Math.abs(test.duration - v.currentTime) < 0.1,
        token + " Current time should be same as duration");
+
     // Verify all sessions had all keys went sent the to the CDM usable, and thus
     // that we received keyschange event(s).
-    var sessions = v.mediaKeys.sessions;
     is(sessions.length, 1, "should have 1 session");
     for (var i = 0; i < sessions.length; i++) {
       var session = sessions[i];
       ok(session.gotKeysChanged, "Should have received at least one keychange event");
       for (var kid in session.keyIdsReceived) {
         ok(session.keyIdsReceived[kid], "key with id " + kid + " was usable as expected");
       }
     }
-  });
+
+   });
 
   v.addEventListener("error", bail(token + " got error event"));
 
-  PlayTest(test, v);
+  LoadTest(test, v).then(function(){v.play();}, bail(token + " failed to load"));
 }
 
 function testIsTypeSupported()
 {
   var t = MediaKeys.isTypeSupported;
   const clearkey = "org.w3.clearkey";
   ok(!t("bogus", "bogon", "video/bogus"), "Invalid type.");
   ok(t(clearkey), "ClearKey supported.");