Make cc/paint have concrete types

cc/paint/paint_surface.h

Index: cc/paint/paint_surface.h
diff --git a/cc/paint/paint_surface.h b/cc/paint/paint_surface.h
index 34165bf16ed70e74bd47550cc18e707eaef97488..97bbb1a09b382d9169a5524216a6d4408a5e9b91 100644
--- a/cc/paint/paint_surface.h
+++ b/cc/paint/paint_surface.h
@@ -5,10 +5,52 @@
 #ifndef CC_PAINT_PAINT_SURFACE_H_
 #define CC_PAINT_PAINT_SURFACE_H_
 
+#include "base/memory/ptr_util.h"
+#include "cc/paint/paint_canvas.h"
+#include "cc/paint/paint_export.h"
 #include "third_party/skia/include/core/SkSurface.h"
 
 namespace cc {
-using PaintSurface = SkSurface;
-}
+
+class CC_PAINT_EXPORT PaintSurface : public SkRefCntBase {
+ public:
+  ~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_sp<PaintSurface>(new 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_sp<PaintSurface>(new 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_)
+      canvas_ = base::WrapUnique(new PaintCanvas(surface_->getCanvas()));
+    return canvas_.get();
+  }
+
+ private:
+  explicit PaintSurface(sk_sp<SkSurface> surface);
+
+  const sk_sp<SkSurface> surface_;
+  std::unique_ptr<PaintCanvas> canvas_;
+};
+
+}  // namespace cc
 
 #endif  // CC_PAINT_PAINT_SURFACE_H_