Start separating the text track container from the media controls

Source/core/html/track/TextTrackContainer.h

Index: Source/core/html/track/TextTrackContainer.h
diff --git a/Source/platform/audio/AudioIOCallback.h b/Source/core/html/track/TextTrackContainer.h
similarity index 68%
copy from Source/platform/audio/AudioIOCallback.h
copy to Source/core/html/track/TextTrackContainer.h
index fa59684f66c231fd34a3636697bb88941bb62862..baec40d9ecd555ddb9754a0474e6696cc8f420e3 100644
--- a/Source/platform/audio/AudioIOCallback.h
+++ b/Source/core/html/track/TextTrackContainer.h
@@ -1,4 +1,5 @@
 /*
+ * Copyright (C) 2008, 2009, 2010, 2011 Apple Inc. All rights reserved.
  * Copyright (C) 2012 Google Inc. All rights reserved.
  *
  * Redistribution and use in source and binary forms, with or without
@@ -26,23 +27,35 @@
  * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
  */
 
-#ifndef AudioIOCallback_h
-#define AudioIOCallback_h
+#ifndef TextTrackContainer_h
+#define TextTrackContainer_h
+
+#include "core/html/HTMLDivElement.h"
 
 namespace blink {
 
-class AudioBus;
+class HTMLMediaElement;
 
-// Abstract base-class for isochronous audio I/O client.
-class AudioIOCallback {
+class TextTrackContainer final : public HTMLDivElement {
 public:
-    // render() is called periodically to get the next render quantum of audio into destinationBus.
-    // Optional audio input is given in sourceBus (if it's not 0).
-    virtual void render(AudioBus* sourceBus, AudioBus* destinationBus, size_t framesToProcess) = 0;
+    static PassRefPtrWillBeRawPtr<TextTrackContainer> create(Document&);
+
+    void updateDisplay(HTMLMediaElement&);
+    void updateSizes(LayoutObject*);
+
+private:
+    TextTrackContainer(Document&);
 
-    virtual ~AudioIOCallback() { }
+    virtual bool isTextTrackContainer() const override { return true; }
+
+    virtual LayoutObject* createLayoutObject(const LayoutStyle&) override;
+
+    IntSize m_videoSize;
+    float m_fontSize;
 };
 
+DEFINE_ELEMENT_TYPE_CASTS(TextTrackContainer, isTextTrackContainer());
+
 } // namespace blink
 
-#endif // AudioIOCallback_h
+#endif // TextTrackContainer_h