[WIP] Re-implement MediaControls in Blink-in-JS

Source/core/html/shadow/MediaControls.cpp

 /*
  * Copyright (C) 2011, 2012 Apple Inc. All rights reserved.
  * Copyright (C) 2011, 2012 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
  * modification, are permitted provided that the following conditions
  * are met:
  * 1. Redistributions of source code must retain the above copyright
  *    notice, this list of conditions and the following disclaimer.
  * 2. Redistributions in binary form must reproduce the above copyright
@@ skipping 10 matching lines @@
  * PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY
  * OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
  * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
  * OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
 #include "config.h"
 #include "core/html/shadow/MediaControls.h"
 
 #include "bindings/core/v8/ExceptionStatePlaceholder.h"
+#include "bindings/core/v8/V8MediaControls.h"
+#include "bindings/core/v8/PrivateScriptRunner.h"
 #include "core/events/MouseEvent.h"
 #include "core/frame/Settings.h"
 #include "core/html/HTMLMediaElement.h"
+#include "core/html/HTMLVideoElement.h"
 #include "core/html/MediaController.h"
 #include "core/rendering/RenderTheme.h"
+#include "core/rendering/RenderVideo.h"
+#include "wtf/text/Base64.h"
 
 namespace blink {
 
 // If you change this value, then also update the corresponding value in
 // LayoutTests/media/media-controls.js.
-static const double timeWithoutMouseMovementBeforeHidingMediaControls = 3;
+//static const double timeWithoutMouseMovementBeforeHidingMediaControls = 3;
 
 static bool fullscreenIsSupported(const Document& document)
 {
     return !document.settings() || document.settings()->fullscreenSupported();
 }
 
 static bool deviceSupportsMouse(const Document& document)
 {
     return !document.settings() || document.settings()->deviceSupportsMouse();
 }
 
 MediaControls::MediaControls(HTMLMediaElement& mediaElement)
     : HTMLDivElement(mediaElement.document())
     , m_mediaElement(&mediaElement)
     , m_panel(nullptr)
     , m_textDisplayContainer(nullptr)
     , m_overlayPlayButton(nullptr)
     , m_overlayEnclosure(nullptr)
     , m_playButton(nullptr)
     , m_currentTimeDisplay(nullptr)
     , m_timeline(nullptr)
     , m_muteButton(nullptr)
     , m_volumeSlider(nullptr)
     , m_toggleClosedCaptionsButton(nullptr)
     , m_fullScreenButton(nullptr)
     , m_durationDisplay(nullptr)
     , m_enclosure(nullptr)
     , m_hideMediaControlsTimer(this, &MediaControls::hideMediaControlsTimerFired)
-    , m_isMouseOverControls(false)
-    , m_isPausedForScrubbing(false)
+      //, m_isMouseOverControls(false)
+      //, m_isPausedForScrubbing(false)
 {
+    ScriptWrappable::init(this);
+    v8::Handle<v8::Value> classObject = PrivateScriptRunner::installClassIfNeeded(document().frame(), "MediaControls");
+    RELEASE_ASSERT(!classObject.IsEmpty());
 }
 
 PassRefPtrWillBeRawPtr<MediaControls> MediaControls::create(HTMLMediaElement& mediaElement)
 {
     RefPtrWillBeRawPtr<MediaControls> controls = adoptRefWillBeNoop(new MediaControls(mediaElement));
 
-    if (controls->initializeControls())
-        return controls.release();
+    /*if (!controls->initializeControls())
+      return nullptr;*/
 
-    return nullptr;
+    PassRefPtrWillBeRawPtr<HTMLMediaElement> media(&mediaElement);
+    if (!V8MediaControls::PrivateScript::createdCallbackMethod(controls->document().frame(), controls.get(), media))
+        return nullptr;
+
+    return controls.release();
 }
 
 bool MediaControls::initializeControls()
 {
     TrackExceptionState exceptionState;
 
     if (document().settings() && document().settings()->mediaControlsOverlayPlayButtonEnabled()) {
         RefPtrWillBeRawPtr<MediaControlOverlayEnclosureElement> overlayEnclosure = MediaControlOverlayEnclosureElement::create(*this);
         RefPtrWillBeRawPtr<MediaControlOverlayPlayButtonElement> overlayPlayButton = MediaControlOverlayPlayButtonElement::create(*this);
         m_overlayPlayButton = overlayPlayButton.get();
@@ skipping 69 matching lines @@
     m_enclosure = enclosure.get();
     appendChild(enclosure.release(), exceptionState);
     if (exceptionState.hadException())
         return false;
 
     return true;
 }
 
 void MediaControls::reset()
 {
-    double duration = mediaElement().duration();
+    /*double duration = mediaElement().duration();
     m_durationDisplay->setInnerText(RenderTheme::theme().formatMediaControlsTime(duration), ASSERT_NO_EXCEPTION);
     m_durationDisplay->setCurrentValue(duration);
 
     updatePlayState();
 
     updateCurrentTimeDisplay();
 
     m_timeline->setDuration(duration);
     m_timeline->setPosition(mediaElement().currentTime());
 
     if (!mediaElement().hasAudio())
         m_volumeSlider->hide();
     else
         m_volumeSlider->show();
     updateVolume();
 
     refreshClosedCaptionsButtonVisibility();
 
-    if (mediaElement().hasVideo() && fullscreenIsSupported(document()))
+    if (mediaElement().hasVideo() && fullscreenIsSupported())
         m_fullScreenButton->show();
     else
         m_fullScreenButton->hide();
 
-    makeOpaque();
+    makeOpaque();*/
+
+    V8MediaControls::PrivateScript::resetMethod(document().frame(), this);
 }
 
 void MediaControls::show()
 {
-    makeOpaque();
+    /*makeOpaque();
     m_panel->setIsDisplayed(true);
     m_panel->show();
     if (m_overlayPlayButton)
-        m_overlayPlayButton->updateDisplayType();
+    m_overlayPlayButton->updateDisplayType();*/
+
+    V8MediaControls::PrivateScript::showMethod(document().frame(), this);
 }
 
 void MediaControls::mediaElementFocused()
 {
-    show();
-    stopHideMediaControlsTimer();
+    /*show();
+      stopHideMediaControlsTimer();*/
+
+    V8MediaControls::PrivateScript::mediaElementFocusedMethod(document().frame(), this);
 }
 
 void MediaControls::hide()
 {
-    m_panel->setIsDisplayed(false);
+    /*m_panel->setIsDisplayed(false);
     m_panel->hide();
     if (m_overlayPlayButton)
-        m_overlayPlayButton->hide();
+    m_overlayPlayButton->hide();*/
+
+    V8MediaControls::PrivateScript::hideMethod(document().frame(), this);
 }
 
 void MediaControls::makeOpaque()
 {
-    m_panel->makeOpaque();
+    //m_panel->makeOpaque();
 }
 
 void MediaControls::makeTransparent()
 {
-    m_panel->makeTransparent();
+    //m_panel->makeTransparent();
 }
 
 bool MediaControls::shouldHideMediaControls(unsigned behaviorFlags) const
 {
-    // Never hide for a media element without visual representation.
+    /*// Never hide for a media element without visual representation.
     if (!mediaElement().hasVideo())
         return false;
     // Don't hide if the mouse is over the controls.
     const bool ignoreControlsHover = behaviorFlags & IgnoreControlsHover;
     if (!ignoreControlsHover && m_panel->hovered())
         return false;
     // Don't hide if the mouse is over the video area.
     const bool ignoreVideoHover = behaviorFlags & IgnoreVideoHover;
     if (!ignoreVideoHover && m_isMouseOverControls)
         return false;
     // Don't hide if focus is on the HTMLMediaElement or within the
     // controls/shadow tree. (Perform the checks separately to avoid going
     // through all the potential ancestor hosts for the focused element.)
     const bool ignoreFocus = behaviorFlags & IgnoreFocus;
     if (!ignoreFocus && (mediaElement().focused() || contains(document().focusedElement())))
         return false;
-    return true;
+        return true;*/
+
+    return false;
 }
 
 void MediaControls::playbackStarted()
 {
-    m_currentTimeDisplay->show();
+    /* m_currentTimeDisplay->show();
     m_durationDisplay->hide();
 
     updatePlayState();
     m_timeline->setPosition(mediaElement().currentTime());
     updateCurrentTimeDisplay();
 
-    startHideMediaControlsTimer();
+    startHideMediaControlsTimer();*/
+
+    V8MediaControls::PrivateScript::playbackStartedMethod(document().frame(), this);
 }
 
 void MediaControls::playbackProgressed()
 {
-    m_timeline->setPosition(mediaElement().currentTime());
+    /*m_timeline->setPosition(mediaElement().currentTime());
     updateCurrentTimeDisplay();
 
     if (shouldHideMediaControls())
-        makeTransparent();
+    makeTransparent();*/
+
+    V8MediaControls::PrivateScript::playbackProgressedMethod(document().frame(), this);
 }
 
 void MediaControls::playbackStopped()
 {
-    updatePlayState();
+    /*updatePlayState();
     m_timeline->setPosition(mediaElement().currentTime());
     updateCurrentTimeDisplay();
     makeOpaque();
 
-    stopHideMediaControlsTimer();
+    stopHideMediaControlsTimer();*/
+
+    V8MediaControls::PrivateScript::playbackStoppedMethod(document().frame(), this);
 }
 
 void MediaControls::updatePlayState()
 {
-    if (m_isPausedForScrubbing)
+    /*if (m_isPausedForScrubbing)
         return;
 
     if (m_overlayPlayButton)
         m_overlayPlayButton->updateDisplayType();
-    m_playButton->updateDisplayType();
+        m_playButton->updateDisplayType();*/
 }
 
 void MediaControls::beginScrubbing()
 {
-    if (!mediaElement().togglePlayStateWillPlay()) {
+    /*if (!mediaElement().togglePlayStateWillPlay()) {
         m_isPausedForScrubbing = true;
         mediaElement().togglePlayState();
-    }
+        }*/
+
+    V8MediaControls::PrivateScript::beginScrubbingMethod(document().frame(), this);
 }
 
 void MediaControls::endScrubbing()
 {
-    if (m_isPausedForScrubbing) {
+    /*if (m_isPausedForScrubbing) {
         m_isPausedForScrubbing = false;
         if (mediaElement().togglePlayStateWillPlay())
             mediaElement().togglePlayState();
-    }
+            }*/
+
+    V8MediaControls::PrivateScript::endScrubbingMethod(document().frame(), this);
 }
 
 void MediaControls::updateCurrentTimeDisplay()
 {
-    double now = mediaElement().currentTime();
+    /*double now = mediaElement().currentTime();
     double duration = mediaElement().duration();
 
     // After seek, hide duration display and show current time.
     if (now > 0) {
         m_currentTimeDisplay->show();
         m_durationDisplay->hide();
     }
 
     // Allow the theme to format the time.
     m_currentTimeDisplay->setInnerText(RenderTheme::theme().formatMediaControlsCurrentTime(now, duration), IGNORE_EXCEPTION);
-    m_currentTimeDisplay->setCurrentValue(now);
+    m_currentTimeDisplay->setCurrentValue(now);*/
+
+    V8MediaControls::PrivateScript::updateCurrentTimeDisplayMethod(document().frame(), this);
 }
 
 void MediaControls::updateVolume()
 {
-    m_muteButton->updateDisplayType();
+    /*m_muteButton->updateDisplayType();
     if (m_muteButton->renderer())
         m_muteButton->renderer()->setShouldDoFullPaintInvalidation(true);
 
     if (mediaElement().muted())
         m_volumeSlider->setVolume(0);
     else
-        m_volumeSlider->setVolume(mediaElement().volume());
+    m_volumeSlider->setVolume(mediaElement().volume());*/
+
+    V8MediaControls::PrivateScript::updateVolumeMethod(document().frame(), this);
 }
 
 void MediaControls::changedClosedCaptionsVisibility()
 {
-    m_toggleClosedCaptionsButton->updateDisplayType();
+    //m_toggleClosedCaptionsButton->updateDisplayType();
+
+    V8MediaControls::PrivateScript::changedClosedCaptionsVisibilityMethod(document().frame(), this);
 }
 
 void MediaControls::refreshClosedCaptionsButtonVisibility()
 {
-    if (mediaElement().hasClosedCaptions())
+    /*if (mediaElement().hasClosedCaptions())
         m_toggleClosedCaptionsButton->show();
     else
-        m_toggleClosedCaptionsButton->hide();
+    m_toggleClosedCaptionsButton->hide();*/
+
+    V8MediaControls::PrivateScript::refreshClosedCaptionsButtonVisibilityMethod(document().frame(), this);
 }
 
 void MediaControls::closedCaptionTracksChanged()
 {
-    refreshClosedCaptionsButtonVisibility();
+    //refreshClosedCaptionsButtonVisibility();
+
+    V8MediaControls::PrivateScript::closedCaptionTracksChangedMethod(document().frame(), this);
 }
 
 void MediaControls::enteredFullscreen()
 {
-    m_fullScreenButton->setIsFullscreen(true);
+    /*m_fullScreenButton->setIsFullscreen(true);
     stopHideMediaControlsTimer();
-    startHideMediaControlsTimer();
+    startHideMediaControlsTimer();*/
+
+    V8MediaControls::PrivateScript::enteredFullscreenMethod(document().frame(), this);
 }
 
 void MediaControls::exitedFullscreen()
 {
-    m_fullScreenButton->setIsFullscreen(false);
+    /*m_fullScreenButton->setIsFullscreen(false);
     stopHideMediaControlsTimer();
-    startHideMediaControlsTimer();
+    startHideMediaControlsTimer();*/
+
+    V8MediaControls::PrivateScript::exitedFullscreenMethod(document().frame(), this);
 }
 
 void MediaControls::defaultEventHandler(Event* event)
 {
-    HTMLDivElement::defaultEventHandler(event);
+    /*HTMLDivElement::defaultEventHandler(event);
 
     if (event->type() == EventTypeNames::mouseover) {
         if (!containsRelatedTarget(event)) {
             m_isMouseOverControls = true;
             if (!mediaElement().togglePlayStateWillPlay()) {
                 makeOpaque();
                 if (shouldHideMediaControls())
                     startHideMediaControlsTimer();
             }
         }
         return;
     }
 
     if (event->type() == EventTypeNames::mouseout) {
         if (!containsRelatedTarget(event)) {
             m_isMouseOverControls = false;
             stopHideMediaControlsTimer();
         }
         return;
     }
 
     if (event->type() == EventTypeNames::mousemove) {
         // When we get a mouse move, show the media controls, and start a timer
         // that will hide the media controls after a 3 seconds without a mouse move.
         makeOpaque();
         if (shouldHideMediaControls(IgnoreVideoHover))
             startHideMediaControlsTimer();
         return;
-    }
+        }*/
 }
 
 void MediaControls::hideMediaControlsTimerFired(Timer<MediaControls>*)
 {
-    if (mediaElement().togglePlayStateWillPlay())
+    /*if (mediaElement().togglePlayStateWillPlay())
         return;
 
     unsigned behaviorFlags = IgnoreFocus | IgnoreVideoHover;
     // FIXME: improve this check, see http://www.crbug.com/401177.
     if (!deviceSupportsMouse(document())) {
         behaviorFlags |= IgnoreControlsHover;
     }
     if (!shouldHideMediaControls(behaviorFlags))
         return;
 
-    makeTransparent();
+        makeTransparent();*/
 }
 
 void MediaControls::startHideMediaControlsTimer()
 {
-    m_hideMediaControlsTimer.startOneShot(timeWithoutMouseMovementBeforeHidingMediaControls, FROM_HERE);
+    //m_hideMediaControlsTimer.startOneShot(timeWithoutMouseMovementBeforeHidingMediaControls, FROM_HERE);
 }
 
 void MediaControls::stopHideMediaControlsTimer()
 {
-    m_hideMediaControlsTimer.stop();
+    //m_hideMediaControlsTimer.stop();
 }
 
 const AtomicString& MediaControls::shadowPseudoId() const
 {
     DEFINE_STATIC_LOCAL(AtomicString, id, ("-webkit-media-controls"));
     return id;
 }
 
 bool MediaControls::containsRelatedTarget(Event* event)
 {
-    if (!event->isMouseEvent())
+    /*if (!event->isMouseEvent())
         return false;
     EventTarget* relatedTarget = toMouseEvent(event)->relatedTarget();
     if (!relatedTarget)
         return false;
-    return contains(relatedTarget->toNode());
+        return contains(relatedTarget->toNode());*/
+
+    return false;
 }
 
 void MediaControls::createTextTrackDisplay()
 {
-    if (m_textDisplayContainer)
+    /*if (m_textDisplayContainer)
         return;
 
     RefPtrWillBeRawPtr<MediaControlTextTrackContainerElement> textDisplayContainer = MediaControlTextTrackContainerElement::create(*this);
     m_textDisplayContainer = textDisplayContainer.get();
 
     // Insert it before (behind) all other control elements.
     if (m_overlayEnclosure && m_overlayPlayButton)
         m_overlayEnclosure->insertBefore(textDisplayContainer.release(), m_overlayPlayButton);
     else
-        insertBefore(textDisplayContainer.release(), m_enclosure);
+    insertBefore(textDisplayContainer.release(), m_enclosure);*/
 }
 
 void MediaControls::showTextTrackDisplay()
 {
-    if (!m_textDisplayContainer)
+    /*if (!m_textDisplayContainer)
         createTextTrackDisplay();
-    m_textDisplayContainer->show();
+        m_textDisplayContainer->show();*/
 }
 
 void MediaControls::hideTextTrackDisplay()
 {
-    if (!m_textDisplayContainer)
+    /*if (!m_textDisplayContainer)
         createTextTrackDisplay();
-    m_textDisplayContainer->hide();
+        m_textDisplayContainer->hide();*/
 }
 
 void MediaControls::updateTextTrackDisplay()
 {
-    if (!m_textDisplayContainer)
+    /*if (!m_textDisplayContainer)
         createTextTrackDisplay();
 
-    m_textDisplayContainer->updateDisplay();
+        m_textDisplayContainer->updateDisplay();*/
+}
+
+String MediaControls::getResourceDataURL(String name)
+{
+    // FIXME: Use cache
+    Image* image = Image::loadPlatformResource(name.utf8().data()).leakRef();
+
+    // FIXME: This depends on the fact the resource image is PNG.
+    Vector<char> imageData;
+    imageData.append(image->data()->data(), image->data()->size());
+    Vector<char> base64Data;
+    WTF::base64Encode(imageData, base64Data);
+    return "data:image/png;base64," + base64Data;
+}
+
+bool MediaControls::isOverlayPlayButtonEnabled()
+{
+    return document().settings() && document().settings()->mediaControlsOverlayPlayButtonEnabled();
+}
+
+bool MediaControls::shouldShowControls() const
+{
+    return mediaElement().shouldShowControls();
+}
+
+bool MediaControls::hasAudio() const
+{
+    return mediaElement().hasAudio();
+}
+
+bool MediaControls::hasVideo() const
+{
+    return mediaElement().hasVideo();
+}
+
+bool MediaControls::hasClosedCaptions() const
+{
+    return mediaElement().hasClosedCaptions();
+}
+
+bool MediaControls::togglePlayStateWillPlay() const
+{
+    return mediaElement().togglePlayStateWillPlay();
+}
+
+void MediaControls::togglePlayState()
+{
+    mediaElement().togglePlayState();
+}
+
+void MediaControls::setCurrentTime(double time)

[philipj_slow, 2014/08/25 09:53:27]

I think this can be implemented in JS as (this.mediaElement_ ||
this.mediaElement_.controller).currentTime = time.

[hajimehoshi, 2014/08/26 04:33:51]

Thanks! I didn't realize that MediaController was already accessible.

+{
+    if (mediaElement().controller())
+        mediaElement().controller()->setCurrentTime(time, IGNORE_EXCEPTION);
+    else
+        mediaElement().setCurrentTime(time, IGNORE_EXCEPTION);
+}
+
+bool MediaControls::isClosedCaptionsVisible() const
+{
+    return mediaElement().closedCaptionsVisible();
+}
+
+void MediaControls::toggleClosedCaptionsVisible()
+{
+    mediaElement().setClosedCaptionsVisible(!mediaElement().closedCaptionsVisible());
+}
+
+void MediaControls::toggleFullscreen()
+{
+    if (mediaElement().isFullscreen())
+        mediaElement().exitFullscreen();
+    else
+        mediaElement().enterFullscreen();
+}
+
+void MediaControls::setDivDisplayType(RefPtrWillBeRawPtr<HTMLElement> element, unsigned type)
+{
+    RefPtrWillBeRawPtr<MediaControlDivElement> mediaDivElement = static_pointer_cast<MediaControlDivElement>(element);
+    mediaDivElement->setDisplayType(static_cast<MediaControlElementType>(type));
+}
+
+void MediaControls::setInputDisplayType(RefPtrWillBeRawPtr<HTMLElement> element, unsigned type)
+{
+    //RefPtrWillBeRawPtr<MediaControlInputElement> mediaInputElement = static_pointer_cast<MediaControlInputElement>(element);
+    // This doesn't work!!!
+    //mediaInputElement->setDisplayType(static_cast<MediaControlElementType>(type));
+}
+
+bool MediaControls::fullscreenIsSupported() const
+{
+    return blink::fullscreenIsSupported(document());
+}
+
+double MediaControls::getTextTrackContainerFontSize()
+{
+    if (!document().isActive())
+        return 0;
+
+    IntRect videoBox;
+
+    if (!mediaElement().renderer() || !mediaElement().renderer()->isVideo())
+        return 0;
+    videoBox = toRenderVideo(mediaElement().renderer())->videoBox();
+
+    m_videoDisplaySize = videoBox;
+
+    float smallestDimension = std::min(videoBox.size().height(), videoBox.size().width());
+
+    return smallestDimension * 0.05f;
+}
+
+void MediaControls::updateTextTrackContainerDisplay(RefPtrWillBeRawPtr<HTMLElement> textTrackContainer)
+{
+    if (!mediaElement().closedCaptionsVisible()) {
+        textTrackContainer->removeChildren();
+        return;
+    }
+
+    // 1. If the media element is an audio element, or is another playback
+    // mechanism with no rendering area, abort these steps. There is nothing to
+    // render.
+    if (isHTMLAudioElement(mediaElement()))
+        return;
+
+    // 2. Let video be the media element or other playback mechanism.
+    HTMLVideoElement& video = toHTMLVideoElement(mediaElement());
+
+    // 3. Let output be an empty list of absolutely positioned CSS block boxes.
+
+    // 4. If the user agent is exposing a user interface for video, add to
+    // output one or more completely transparent positioned CSS block boxes that
+    // cover the same region as the user interface.
+
+    // 5. If the last time these rules were run, the user agent was not exposing
+    // a user interface for video, but now it is, let reset be true. Otherwise,
+    // let reset be false.
+
+    // There is nothing to be done explicitly for 4th and 5th steps, as
+    // everything is handled through CSS. The caption box is on top of the
+    // controls box, in a container set with the -webkit-box display property.
+
+    // 6. Let tracks be the subset of video's list of text tracks that have as
+    // their rules for updating the text track rendering these rules for
+    // updating the display of WebVTT text tracks, and whose text track mode is
+    // showing or showing by default.
+    // 7. Let cues be an empty list of text track cues.
+    // 8. For each track track in tracks, append to cues all the cues from
+    // track's list of cues that have their text track cue active flag set.
+    CueList activeCues = video.currentlyActiveCues();
+
+    // 9. If reset is false, then, for each text track cue cue in cues: if cue's
+    // text track cue display state has a set of CSS boxes, then add those boxes
+    // to output, and remove cue from cues.
+
+    // There is nothing explicitly to be done here, as all the caching occurs
+    // within the TextTrackCue instance itself. If parameters of the cue change,
+    // the display tree is cleared.
+
+    // 10. For each text track cue cue in cues that has not yet had
+    // corresponding CSS boxes added to output, in text track cue order, run the
+    // following substeps:
+    for (size_t i = 0; i < activeCues.size(); ++i) {
+        TextTrackCue* cue = activeCues[i].data();
+
+        ASSERT(cue->isActive());
+        if (!cue->track() || !cue->track()->isRendered() || !cue->isActive())
+            continue;
+
+        cue->updateDisplay(m_videoDisplaySize.size(), *this);
+    }
 }
 
 void MediaControls::trace(Visitor* visitor)
 {
     visitor->trace(m_mediaElement);
     visitor->trace(m_panel);
     visitor->trace(m_textDisplayContainer);
     visitor->trace(m_overlayPlayButton);
     visitor->trace(m_overlayEnclosure);
     visitor->trace(m_playButton);
     visitor->trace(m_currentTimeDisplay);
     visitor->trace(m_timeline);
     visitor->trace(m_muteButton);
     visitor->trace(m_volumeSlider);
     visitor->trace(m_toggleClosedCaptionsButton);
     visitor->trace(m_fullScreenButton);
     visitor->trace(m_durationDisplay);
     visitor->trace(m_enclosure);
     HTMLDivElement::trace(visitor);
 }
 
 }