Revert of Make cc/paint have concrete types

cc/paint/paint_surface.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_PAINT_SURFACE_H_
 #define CC_PAINT_PAINT_SURFACE_H_
 
-#include "base/macros.h"
-#include "base/memory/ptr_util.h"
-#include "base/optional.h"
-#include "cc/paint/paint_canvas.h"
-#include "cc/paint/paint_export.h"
 #include "third_party/skia/include/core/SkSurface.h"
 
 namespace cc {
-
-class CC_PAINT_EXPORT PaintSurface : public SkRefCntBase {
- public:
-  explicit PaintSurface(sk_sp<SkSurface> surface);
-  ~PaintSurface() override;
-
-  // TODO(enne): this interface matches SkSurface for simplicity.
-  // However, this should really be changed to make the SkSurface ctor
-  // public and have that be the only constructor.  This will also
-  // clean up a bunch of code where there's an SkSurface and a PaintCanvas,
-  // such as for canvas in Blink.
-  static sk_sp<PaintSurface> MakeRaster(const SkImageInfo& info,
-                                        const SkSurfaceProps* props = nullptr) {
-    sk_sp<SkSurface> s = SkSurface::MakeRaster(info, props);
-    return sk_make_sp<PaintSurface>(std::move(s));
-  }
-  static sk_sp<PaintSurface> MakeRasterN32Premul(
-      int width,
-      int height,
-      const SkSurfaceProps* props = nullptr) {
-    sk_sp<SkSurface> s = SkSurface::MakeRasterN32Premul(width, height, props);
-    return sk_make_sp<PaintSurface>(std::move(s));
-  }
-
-  int width() const { return surface_->width(); }
-  int height() const { return surface_->height(); }
-  uint32_t generationID() { return surface_->generationID(); }
-
-  PaintCanvas* getCanvas() {
-    if (!canvas_.has_value())
-      canvas_.emplace(surface_->getCanvas());
-    return &canvas_.value();
-  }
-
- private:
-  const sk_sp<SkSurface> surface_;
-  base::Optional<PaintCanvas> canvas_;
-
-  DISALLOW_COPY_AND_ASSIGN(PaintSurface);
-};
-
-}  // namespace cc
+using PaintSurface = SkSurface;
+}
 
 #endif  // CC_PAINT_PAINT_SURFACE_H_