cc: Make PaintCanvas abstract

cc/layers/painted_overlay_scrollbar_layer.cc

Index: cc/layers/painted_overlay_scrollbar_layer.cc
diff --git a/cc/layers/painted_overlay_scrollbar_layer.cc b/cc/layers/painted_overlay_scrollbar_layer.cc
index eea22c63051043711eebc0a3417553439869e0be..df323479d491beefb789fadc7e550a36b538f2b6 100644
--- a/cc/layers/painted_overlay_scrollbar_layer.cc
+++ b/cc/layers/painted_overlay_scrollbar_layer.cc
@@ -9,6 +9,7 @@
 #include "base/auto_reset.h"
 #include "cc/base/math_util.h"
 #include "cc/layers/painted_overlay_scrollbar_layer_impl.h"
+#include "cc/paint/skia_paint_canvas.h"
 #include "cc/resources/ui_resource_bitmap.h"
 #include "cc/resources/ui_resource_manager.h"
 #include "cc/trees/layer_tree_host.h"
@@ -148,7 +149,7 @@ bool PaintedOverlayScrollbarLayer::PaintThumbIfNeeded() {
 
   SkBitmap skbitmap;
   skbitmap.allocN32Pixels(paint_rect.width(), paint_rect.height());
-  PaintCanvas canvas(skbitmap);
+  SkiaPaintCanvas canvas(skbitmap);
 
   SkRect content_skrect = RectToSkRect(paint_rect);
   PaintFlags flags;