ui/gfx: Make gfx::Canvas inherit from gfx::CanvasSkia.

ui/views/native_theme_painter.h

Index: ui/views/native_theme_painter.h
diff --git a/ui/views/native_theme_painter.h b/ui/views/native_theme_painter.h
index 1dcb75f060b76d429e32770ff1a951cb9e11d4ec..7e52734f8adcd2c813e0e04480b37692964b9dd2 100644
--- a/ui/views/native_theme_painter.h
+++ b/ui/views/native_theme_painter.h
@@ -10,7 +10,7 @@
 #include "ui/views/painter.h"
 
 namespace gfx {
-class Canvas;
+class CanvasSkia;
 class Size;
 }
 
@@ -35,7 +35,7 @@ class VIEWS_EXPORT NativeThemePainter : public Painter {
   NativeThemeDelegate* delegate_;
 
   // Overridden from Painter:
-  virtual void Paint(gfx::Canvas* canvas, const gfx::Size& size) OVERRIDE;
+  virtual void Paint(gfx::CanvasSkia* canvas, const gfx::Size& size) OVERRIDE;
 
   DISALLOW_COPY_AND_ASSIGN(NativeThemePainter);
 };