New media playback UI.

Source/core/layout/LayoutThemeMac.mm

Index: Source/core/layout/LayoutThemeMac.mm
diff --git a/Source/core/layout/LayoutThemeMac.mm b/Source/core/layout/LayoutThemeMac.mm
index 2c03a9cc304b759c56b5a9af8c78e0097d8a0017..d158a923cbbaed9819242c64b193a1d84f4d44d7 100644
--- a/Source/core/layout/LayoutThemeMac.mm
+++ b/Source/core/layout/LayoutThemeMac.mm
@@ -1015,9 +1015,9 @@ void LayoutThemeMac::adjustSliderThumbSize(ComputedStyle& style, Element*) const
     if (style.appearance() == SliderThumbHorizontalPart || style.appearance() == SliderThumbVerticalPart) {
         style.setWidth(Length(static_cast<int>(sliderThumbWidth * zoomLevel), Fixed));
         style.setHeight(Length(static_cast<int>(sliderThumbHeight * zoomLevel), Fixed));
+    } else {
+        adjustMediaSliderThumbSize(style);

[philipj_slow, 2015/07/08 10:31:52]

Why was this change needed?

[liberato (no reviews please), 2015/07/09 12:10:56]

the original adjust..Size() did nothing unless the slider type was one of the
two media sliders.  the new one does, since it does the same thing in both
cases.

i considered keeping the old behavior there, and not adding the 'else'. 
however, the else seemed less flaky and matches what ThemeDefault does already.

     }
-
-    adjustMediaSliderThumbSize(style);
 }
 
 NSPopUpButtonCell* LayoutThemeMac::popupButton() const