Support text track selection in video controls

Source/core/html/shadow/MediaControls.cpp

Index: Source/core/html/shadow/MediaControls.cpp
diff --git a/Source/core/html/shadow/MediaControls.cpp b/Source/core/html/shadow/MediaControls.cpp
index b0560f11dddbc156a7e77c71ccca1c75b39140a6..e5e0fbd199e8e6e72e375358938e92338c059f07 100644
--- a/Source/core/html/shadow/MediaControls.cpp
+++ b/Source/core/html/shadow/MediaControls.cpp
@@ -59,6 +59,7 @@ MediaControls::MediaControls(HTMLMediaElement& mediaElement)
     , m_muteButton(nullptr)
     , m_volumeSlider(nullptr)
     , m_toggleClosedCaptionsButton(nullptr)
+    , m_textTrackList(nullptr)
     , m_fullScreenButton(nullptr)
     , m_castButton(nullptr)
     , m_overlayCastButton(nullptr)
@@ -95,6 +96,7 @@ PassRefPtrWillBeRawPtr<MediaControls> MediaControls::create(HTMLMediaElement& me
 //     +-MediaControlMuteButtonElement                 (-webkit-media-controls-mute-button)
 //     +-MediaControlVolumeSliderElement               (-webkit-media-controls-volume-slider)
 //     +-MediaControlToggleClosedCaptionsButtonElement (-webkit-media-controls-toggle-closed-captions-button)
+//     +-MediaControlTextTrackListElement              (-internal-media-controls-text-track-list)

[philipj_slow, 2015/05/05 14:36:57]

Can you also document what the internal structure of this looks like, even if it
isn't always created?

[srivats, 2016/02/23 01:39:27]

Done

 //     +-MediaControlCastButtonElement                 (-internal-media-controls-cast-button)
 //     \-MediaControlFullscreenButtonElement           (-webkit-media-controls-fullscreen-button)
 void MediaControls::initializeControls()
@@ -159,6 +161,11 @@ void MediaControls::initializeControls()
     m_panel = panel.get();
     enclosure->appendChild(panel.release());
 
+    RefPtrWillBeRawPtr<MediaControlTextTrackListElement> textTrackList =
+        MediaControlTextTrackListElement::create(*this);
+    m_textTrackList = textTrackList.get();
+    enclosure->appendChild(textTrackList.release());
+
     m_enclosure = enclosure.get();
     appendChild(enclosure.release());
 }
@@ -354,6 +361,19 @@ void MediaControls::refreshClosedCaptionsButtonVisibility()
         m_toggleClosedCaptionsButton->hide();
 }
 
+void MediaControls::toggleTextTrackList()
+{
+    if (!mediaElement().hasClosedCaptions())
+        return;
+
+    if (m_textTrackList->isVisible()) {
+        m_textTrackList->hide();
+    } else {
+        m_textTrackList->refreshTextTrackListMenu();
+        m_textTrackList->show();
+    }
+}
+
 static Element* elementFromCenter(Element& element)
 {
     RefPtrWillBeRawPtr<ClientRect> clientRect = element.getBoundingClientRect();