Factor painting code out of RenderBox into a new class called BoxPainter.

Source/core/rendering/RenderFieldset.h

Index: Source/core/rendering/RenderFieldset.h
diff --git a/Source/core/rendering/RenderFieldset.h b/Source/core/rendering/RenderFieldset.h
index 3096c568835fb747fa888c99f5de78c0dc8226e1..ce83589f768c3464d6a65a4cb75eefe8e97ad307 100644
--- a/Source/core/rendering/RenderFieldset.h
+++ b/Source/core/rendering/RenderFieldset.h
@@ -46,6 +46,8 @@ private:
 
     virtual void paintBoxDecorationBackground(PaintInfo&, const LayoutPoint&) OVERRIDE;
     virtual void paintMask(PaintInfo&, const LayoutPoint&) OVERRIDE;
+
+    BoxPainter m_boxPainter;

[Stephen Chennney, 2014/09/09 16:14:37]

This is what I was getting at earlier. Ideally this would be a FieldsetPainter
that derived from BoxPainter to implement the functionality. Or we use static
painter methods.

[chrishtr, 2014/09/09 16:55:45]

I'm trying to avoid inheritance for implementing the paint code, and instead
using a composition pattern. I think this will result in more understandable
code. Right now this use of BoxPainter code is a little strange, because it's
using BoxPainter as a helper library. Instead I expect we will end up with some
shared libraries factored out of the painters.
The change to this file is what seems a minimal step to unblock creating
BoxPainter, we should refactor within paint/ later.

[Stephen Chennney, 2014/09/09 19:16:48]

Acknowledged.

 };
 
 DEFINE_RENDER_OBJECT_TYPE_CASTS(RenderFieldset, isFieldset());