Clean up MediaControlElement virtual and unused functions

Source/core/html/shadow/MediaControlElementTypes.cpp

Index: Source/core/html/shadow/MediaControlElementTypes.cpp
diff --git a/Source/core/html/shadow/MediaControlElementTypes.cpp b/Source/core/html/shadow/MediaControlElementTypes.cpp
index dc7f986e04e2a68b1a19d40f8400e59bbc30116d..f8e0d5f2df0f0ef76c0bba4f4d8c2c419043371a 100644
--- a/Source/core/html/shadow/MediaControlElementTypes.cpp
+++ b/Source/core/html/shadow/MediaControlElementTypes.cpp
@@ -82,14 +82,6 @@ void MediaControlElement::show()
     m_element->removeInlineStyleProperty(CSSPropertyDisplay);
 }
 
-bool MediaControlElement::isShowing() const
-{
-    const StylePropertySet* propertySet = m_element->inlineStyle();
-    // Following the code from show() and hide() above, we only have
-    // to check for the presense of inline display.
-    return (!propertySet || !propertySet->getPropertyCSSValue(CSSPropertyDisplay));
-}
-
 void MediaControlElement::setDisplayType(MediaControlElementType displayType)
 {
     if (displayType == m_displayType)