https://bugs.webkit.org/show_bug.cgi?id=124421

Reviewed by Eric Carlson.

Currently, VideoTrackPrivateAVFObjC and AudioTrackPrivateAVFObjC are initialized with an
AVPlayerItemTrack, but most of its methods use the AVAssetTrack wrapped by the
AVPlayerItemTrack. Allow these objects to be alternatively initialized with an AVAssetTrack.

Add factory methods taking an AVAssetTrack:
* platform/graphics/avfoundation/objc/AudioTrackPrivateAVFObjC.h:
(WebCore::AudioTrackPrivateAVFObjC::create):
* platform/graphics/avfoundation/objc/AudioTrackPrivateAVFObjC.mm:
(WebCore::AudioTrackPrivateAVFObjC::AudioTrackPrivateAVFObjC):
(WebCore::AudioTrackPrivateAVFObjC::setAssetTrack):
(WebCore::AudioTrackPrivateAVFObjC::assetTrack):
* platform/graphics/avfoundation/objc/VideoTrackPrivateAVFObjC.cpp:
(WebCore::VideoTrackPrivateAVFObjC::VideoTrackPrivateAVFObjC):
(WebCore::VideoTrackPrivateAVFObjC::setAssetTrack):
(WebCore::VideoTrackPrivateAVFObjC::assetTrack):
* platform/graphics/avfoundation/objc/VideoTrackPrivateAVFObjC.h:

Use m_assetTrack instead of [m_playerItemTrack assetTrack]:
* platform/graphics/avfoundation/AVTrackPrivateAVFObjCImpl.h:
(WebCore::AVTrackPrivateAVFObjCImpl::assetTrack):
* platform/graphics/avfoundation/AVTrackPrivateAVFObjCImpl.mm:
(WebCore::AVTrackPrivateAVFObjCImpl::AVTrackPrivateAVFObjCImpl):
(WebCore::AVTrackPrivateAVFObjCImpl::enabled):
(WebCore::AVTrackPrivateAVFObjCImpl::setEnabled):
(WebCore::AVTrackPrivateAVFObjCImpl::audioKind):
(WebCore::AVTrackPrivateAVFObjCImpl::videoKind):
(WebCore::AVTrackPrivateAVFObjCImpl::id):
(WebCore::AVTrackPrivateAVFObjCImpl::label):
(WebCore::AVTrackPrivateAVFObjCImpl::language):
(WebCore::AVTrackPrivateAVFObjCImpl::trackID):

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@159368 268f45cc-cd09-0410-ab3c-d52691b4dbfc