Add ScrollbarTheme to control scrollbar metrics (and eventually hit testing and rendering.

git-svn-id: http://svn.webkit.org/repository/webkit/trunk@36380 268f45cc-cd09-0410-ab3c-d52691b4dbfc
diff --git a/WebCore/platform/ScrollBar.h b/WebCore/platform/ScrollBar.h
index dec745b..024dab2 100644
--- a/WebCore/platform/ScrollBar.h
+++ b/WebCore/platform/ScrollBar.h
@@ -37,6 +37,7 @@
 class GraphicsContext;
 class IntRect;
 class ScrollbarClient;
+class ScrollbarTheme;
 class PlatformMouseEvent;
 
 // These match the numbers we use over in WebKit (WebFrameView.m).
@@ -45,7 +46,7 @@
 
 class Scrollbar : public Widget, public RefCounted<Scrollbar> {
 protected:
-    Scrollbar(ScrollbarClient*, ScrollbarOrientation, ScrollbarControlSize);
+    Scrollbar(ScrollbarClient*, ScrollbarOrientation, ScrollbarControlSize, ScrollbarTheme* = 0);
 
 public:
     virtual ~Scrollbar() {}
@@ -101,6 +102,8 @@
     ScrollbarClient* m_client;
     ScrollbarOrientation m_orientation;
     ScrollbarControlSize m_controlSize;
+    ScrollbarTheme* m_theme;
+    
     int m_visibleSize;
     int m_totalSize;
     float m_currentPos;