Bug 881976 - Part 2: Expose TextTrackList's MediaElement to chrome JS. r=rillian, r=bz

Our JS WebVTT implementation (vtt.js) needs access to a TextTrackList's
MediaElement in order to compute a TextTrackCue's line position. Therefore,
we need to expose it to chrome JS.

content/html/content/src/TextTrackManager.cpp

@@ -32,9 +32,10 @@ TextTrackManager::TextTrackManager(HTMLMediaElement *aMediaElement)
 {
   MOZ_COUNT_CTOR(TextTrackManager);
   mNewCues = new TextTrackCueList(mMediaElement->OwnerDoc()->GetParentObject());
-  mTextTracks = new TextTrackList(mMediaElement->OwnerDoc()->GetParentObject());
+  mTextTracks = new TextTrackList(mMediaElement->OwnerDoc()->GetParentObject(),
+                                  this);
   mPendingTextTracks =
-    new TextTrackList(mMediaElement->OwnerDoc()->GetParentObject());
+    new TextTrackList(mMediaElement->OwnerDoc()->GetParentObject(), this);
 
   if (!sParserWrapper) {
     nsCOMPtr<nsIWebVTTParserWrapper> parserWrapper =

content/html/content/src/TextTrackManager.h

@@ -74,12 +74,12 @@ public:
 
   void PopulatePendingList();
 
-private:
   // The HTMLMediaElement that this TextTrackManager manages the TextTracks of.
   // This is a weak reference as the life time of TextTrackManager is dependent
   // on the HTMLMediaElement, so it should not be trying to hold the
   // HTMLMediaElement alive.
   HTMLMediaElement* mMediaElement;
+private:
   // List of the TextTrackManager's owning HTMLMediaElement's TextTracks.
   nsRefPtr<TextTrackList> mTextTracks;
   // List of text track objects awaiting loading.

content/media/TextTrackList.cpp

@@ -8,14 +8,16 @@
 #include "mozilla/dom/TrackEvent.h"
 #include "nsThreadUtils.h"
 #include "mozilla/dom/TextTrackCue.h"
+#include "mozilla/dom/TextTrackManager.h"
 
 namespace mozilla {
 namespace dom {
 
-NS_IMPL_CYCLE_COLLECTION_INHERITED_2(TextTrackList,
+NS_IMPL_CYCLE_COLLECTION_INHERITED_3(TextTrackList,
                                      nsDOMEventTargetHelper,
                                      mGlobal,
-                                     mTextTracks)
+                                     mTextTracks,
+                                     mTextTrackManager)
 
 NS_IMPL_ADDREF_INHERITED(TextTrackList, nsDOMEventTargetHelper)
 NS_IMPL_RELEASE_INHERITED(TextTrackList, nsDOMEventTargetHelper)
@@ -27,6 +29,13 @@ TextTrackList::TextTrackList(nsISupports* aGlobal) : mGlobal(aGlobal)
   SetIsDOMBinding();
 }
 
+TextTrackList::TextTrackList(nsISupports* aGlobal, TextTrackManager* aTextTrackManager)
+ : mGlobal(aGlobal)
+ , mTextTrackManager(aTextTrackManager)
+{
+  SetIsDOMBinding();
+}
+
 void
 TextTrackList::GetAllActiveCues(nsTArray<nsRefPtr<TextTrackCue> >& aCues)
 {
@@ -159,5 +168,20 @@ TextTrackList::CreateAndDispatchTrackEventRunner(TextTrack* aTrack,
   NS_DispatchToMainThread(eventRunner, NS_DISPATCH_NORMAL);
 }
 
+HTMLMediaElement*
+TextTrackList::GetMediaElement()
+{
+  if (mTextTrackManager) {
+    return mTextTrackManager->mMediaElement;
+  }
+  return nullptr;
+}
+
+void
+TextTrackList::SetTextTrackManager(TextTrackManager* aTextTrackManager)
+{
+  mTextTrackManager = aTextTrackManager;
+}
+
 } // namespace dom
 } // namespace mozilla

content/media/TextTrackList.h

@@ -14,6 +14,8 @@
 namespace mozilla {
 namespace dom {
 
+class HTMLMediaElement;
+class TextTrackManager;
 class TrackEvent;
 class TrackEventRunner;
 
@@ -24,6 +26,7 @@ public:
   NS_DECL_CYCLE_COLLECTION_CLASS_INHERITED(TextTrackList, nsDOMEventTargetHelper)
 
   TextTrackList(nsISupports* aGlobal);
+  TextTrackList(nsISupports* aGlobal, TextTrackManager* aTextTrackManager);
 
   virtual JSObject* WrapObject(JSContext* aCx,
                                JS::Handle<JSObject*> aScope) MOZ_OVERRIDE;
@@ -57,6 +60,9 @@ public:
   void RemoveTextTrack(TextTrack* aTrack);
   void DidSeek();
 
+  HTMLMediaElement* GetMediaElement();
+  void SetTextTrackManager(TextTrackManager* aTextTrackManager);
+
   nsresult DispatchTrackEvent(nsIDOMEvent* aEvent);
   void CreateAndDispatchChangeEvent();
 
@@ -67,6 +73,7 @@ public:
 private:
   nsCOMPtr<nsISupports> mGlobal;
   nsTArray< nsRefPtr<TextTrack> > mTextTracks;
+  nsRefPtr<TextTrackManager> mTextTrackManager;
 
   void CreateAndDispatchTrackEventRunner(TextTrack* aTrack,
                                          const nsAString& aEventName);

content/media/test/chrome.ini

@@ -6,3 +6,4 @@ support-files =
   seek.webm
 
 [test_texttrack_chrome.html]
+[test_texttracklist_chrome.html]

content/media/test/test_texttracklist_chrome.html

@@ -0,0 +1,30 @@
+<!DOCTYPE HTML>
+<html>
+<!--
+https://bugzilla.mozilla.org/show_bug.cgi?id=881976
+-->
+<head>
+  <meta charset='utf-8'>
+  <title>Test for Bug 881976 - TextTrackCue Computed Position</title>
+  <script type="application/javascript" src="chrome://mochikit/content/tests/SimpleTest/SimpleTest.js"></script>
+  <link rel="stylesheet" type="text/css" href="chrome://mochikit/content/tests/SimpleTest/test.css"/>
+</head>
+<body>
+<p id="display"></p>
+<div id="content">
+</div>
+<pre id="test">
+<script class="testbody" type="text/javascript">
+SimpleTest.waitForExplicitFinish();
+SpecialPowers.pushPrefEnv({"set": [["media.webvtt.enabled", true]]},
+  function() {
+    var video = document.createElement("video");
+    is(video.textTracks.mediaElement, video, "Video's TextTrackList's MediaElement reference should be set to the video.");
+    SimpleTest.finish();
+  }
+);
+
+</script>
+</pre>
+</body>
+</html>

dom/webidl/TextTrackList.webidl

@@ -17,3 +17,9 @@ interface TextTrackList : EventTarget {
            attribute EventHandler onaddtrack;
            attribute EventHandler onremovetrack;
 };
+
+// Mozilla extensions
+partial interface TextTrackList {
+  [ChromeOnly]
+  readonly attribute HTMLMediaElement? mediaElement;
+};