Refactor window frame painting into a window background class

ui/views/window/custom_frame_view.h

Index: ui/views/window/custom_frame_view.h
diff --git a/ui/views/window/custom_frame_view.h b/ui/views/window/custom_frame_view.h
index 1ca82bd0ef6b6f89235998089788ff7f07ab1f30..b71c451a9cae647438cd5f3127bb83ffd28875f6 100644
--- a/ui/views/window/custom_frame_view.h
+++ b/ui/views/window/custom_frame_view.h
@@ -10,6 +10,7 @@
 #include "ui/views/widget/widget.h"
 #include "ui/views/window/non_client_view.h"
 
+class SkBitmap;
 namespace gfx {
 class Canvas;
 class Font;
@@ -20,6 +21,8 @@ class Point;
 
 namespace views {
 
+class FrameBackground;
+
 ///////////////////////////////////////////////////////////////////////////////
 //
 // CustomFrameView
@@ -91,6 +94,10 @@ class CustomFrameView : public NonClientFrameView,
   void PaintTitleBar(gfx::Canvas* canvas);
   void PaintRestoredClientEdge(gfx::Canvas* canvas);
 
+  // Compute aspects of the frame needed to paint the frame background.
+  SkColor GetFrameColor() const;
+  SkBitmap* GetFrameBitmap() const;
+
   // Layout various sub-components of this view.
   void LayoutWindowControls();
   void LayoutTitleBar();
@@ -114,6 +121,9 @@ class CustomFrameView : public NonClientFrameView,
   // The window that owns this view.
   Widget* frame_;
 
+  // Background painter for the window frame.
+  scoped_ptr<FrameBackground> frame_background_;
+
   // Initialize various static resources.
   static void InitClass();
   static gfx::Font* title_font_;