Back PaintRecord with PaintOpBuffer instead of SkPicture

cc/paint/skia_paint_canvas.h

 // Copyright 2017 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.
 
 #ifndef CC_PAINT_SKIA_PAINT_CANVAS_H_
 #define CC_PAINT_SKIA_PAINT_CANVAS_H_
 
 #include <memory>
 
 #include "base/compiler_specific.h"
@@ skipping 35 matching lines @@
                   int src_y) override;
   bool readPixels(SkBitmap* bitmap, int src_x, int src_y) override;
   bool readPixels(const SkIRect& srcRect, SkBitmap* bitmap) override;
   bool writePixels(const SkImageInfo& info,
                    const void* pixels,
                    size_t row_bytes,
                    int x,
                    int y) override;
   int save() override;
   int saveLayer(const SkRect* bounds, const PaintFlags* flags) override;
-  int saveLayerAlpha(const SkRect* bounds, U8CPU alpha) override;
+  int saveLayerAlpha(const SkRect* bounds, uint8_t alpha) override;
 
   void restore() override;
   int getSaveCount() const override;
   void restoreToCount(int save_count) override;
   void translate(SkScalar dx, SkScalar dy) override;
   void scale(SkScalar sx, SkScalar sy) override;
   void rotate(SkScalar degrees) override;
   void concat(const SkMatrix& matrix) override;
   void setMatrix(const SkMatrix& matrix) override;
 
@@ skipping 96 matching lines @@
  private:
   SkCanvas* canvas_;
   std::unique_ptr<SkCanvas> owned_;
 
   DISALLOW_COPY_AND_ASSIGN(SkiaPaintCanvas);
 };
 
 }  // namespace cc
 
 #endif  // CC_PAINT_SKIA_PAINT_CANVAS_H_