cc: Make PaintCanvas abstract

cc/layers/painted_overlay_scrollbar_layer.cc

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "cc/layers/painted_overlay_scrollbar_layer.h"
 
 #include <algorithm>
 
 #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"
 #include "cc/trees/layer_tree_impl.h"
 #include "skia/ext/platform_canvas.h"
 #include "third_party/skia/include/core/SkBitmap.h"
 #include "third_party/skia/include/core/SkCanvas.h"
 #include "third_party/skia/include/core/SkSize.h"
 #include "ui/gfx/geometry/size_conversions.h"
 #include "ui/gfx/skia_util.h"
@@ skipping 119 matching lines @@
     return false;
 
   gfx::Rect paint_rect = OriginThumbRectForPainting();
   aperture_ = scrollbar_->NinePatchThumbAperture();
 
   DCHECK(!paint_rect.size().IsEmpty());
   DCHECK(paint_rect.origin().IsOrigin());
 
   SkBitmap skbitmap;
   skbitmap.allocN32Pixels(paint_rect.width(), paint_rect.height());
-  PaintCanvas canvas(skbitmap);
+  SkiaPaintCanvas canvas(skbitmap);
 
   SkRect content_skrect = RectToSkRect(paint_rect);
   PaintFlags flags;
   flags.setAntiAlias(false);
   flags.setBlendMode(SkBlendMode::kClear);
   canvas.drawRect(content_skrect, flags);
   canvas.clipRect(content_skrect);
 
   scrollbar_->PaintPart(&canvas, THUMB, paint_rect);
   // Make sure that the pixels are no longer mutable to unavoid unnecessary
   // allocation and copying.
   skbitmap.setImmutable();
 
   thumb_resource_ = ScopedUIResource::Create(
       layer_tree_host()->GetUIResourceManager(), UIResourceBitmap(skbitmap));
 
   SetNeedsPushProperties();
 
   return true;
 }
 
 }  // namespace cc