Use a ResizeObserver to determine default font-size for text tracks

third_party/WebKit/Source/core/html/HTMLMediaElement.cpp

 /*
  * Copyright (C) 2007, 2008, 2009, 2010, 2011, 2012, 2013 Apple 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 3629 matching lines @@
 }
 
 TextTrackContainer& HTMLMediaElement::ensureTextTrackContainer() {
   ShadowRoot& shadowRoot = ensureUserAgentShadowRoot();
   assertShadowRootChildren(shadowRoot);
 
   Node* firstChild = shadowRoot.firstChild();
   if (firstChild && firstChild->isTextTrackContainer())
     return toTextTrackContainer(*firstChild);
 
-  TextTrackContainer* textTrackContainer =
-      TextTrackContainer::create(document());
+  TextTrackContainer* textTrackContainer = TextTrackContainer::create(*this);
 
   // The text track container should be inserted before the media controls,
   // so that they are rendered behind them.
   shadowRoot.insertBefore(textTrackContainer, firstChild);
 
   assertShadowRootChildren(shadowRoot);
 
   return *textTrackContainer;
 }
 
@@ skipping 588 matching lines @@
       kMostlyFillViewportBecomeStableSeconds, BLINK_FROM_HERE);
 }
 
 void HTMLMediaElement::viewportFillDebouncerTimerFired(TimerBase*) {
   m_mostlyFillingViewport = true;
   if (m_webMediaPlayer)
     m_webMediaPlayer->becameDominantVisibleContent(m_mostlyFillingViewport);
 }
 
 }  // namespace blink