Make cc/paint have concrete types

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"
@@ skipping 122 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());
-  SkCanvas skcanvas(skbitmap);
+  PaintCanvas canvas(skbitmap);
 
   SkRect content_skrect = RectToSkRect(paint_rect);
-  SkPaint paint;
-  paint.setAntiAlias(false);
-  paint.setBlendMode(SkBlendMode::kClear);
-  skcanvas.drawRect(content_skrect, paint);
-  skcanvas.clipRect(content_skrect);
+  PaintFlags flags;
+  flags.setAntiAlias(false);
+  flags.setBlendMode(SkBlendMode::kClear);
+  canvas.drawRect(content_skrect, flags);
+  canvas.clipRect(content_skrect);
 
-  scrollbar_->PaintPart(&skcanvas, THUMB, paint_rect);
+  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