Make cc/paint have concrete types

cc/paint/paint_record.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_RECORD_H_
 #define CC_PAINT_PAINT_RECORD_H_
 
+#include "base/compiler_specific.h"
+#include "base/macros.h"
+#include "cc/paint/paint_export.h"
 #include "third_party/skia/include/core/SkPicture.h"
 #include "third_party/skia/include/utils/SkPictureUtils.h"
 
 namespace cc {
 
-using PaintRecord = SkPicture;
+class PaintCanvas;
 
-inline const SkPicture* ToSkPicture(const PaintRecord* record) {
-  return record;
+class CC_PAINT_EXPORT PaintRecord : private SkPicture {

[vmpstr, 2017/03/03 07:12:08]

This class kinda looks funny, since it has no constructors :P LIke the DISALLOW
COPY prevents the default ctor from being generated so it looks like the class
can't be created, but it's because we're casting from SkPicture xD

Maybe leave a small comment on the class, however temporary, about how an object
of this class is created

+ public:
+  void playback(PaintCanvas* canvas);
+
+  using SkPicture::playback;
+  using SkPicture::approximateBytesUsed;
+  using SkPicture::approximateOpCount;
+  using SkPicture::cullRect;
+  using SkRefCnt::ref;
+  using SkRefCnt::unref;
+
+ private:
+  friend class PaintRecorder;
+  friend const SkPicture* ToSkPicture(const PaintRecord* record);
+  friend SkPicture* ToSkPicture(PaintRecord* record);
+  friend sk_sp<SkPicture> ToSkPicture(sk_sp<PaintRecord> record);
+  friend sk_sp<const SkPicture> ToSkPicture(sk_sp<const PaintRecord> record);
+
+  DISALLOW_COPY_AND_ASSIGN(PaintRecord);
+};
+
+ALWAYS_INLINE const SkPicture* ToSkPicture(const PaintRecord* record) {
+  return static_cast<const SkPicture*>(record);
 }
 
-inline SkPicture* ToSkPicture(PaintRecord* record) {
-  return record;
+ALWAYS_INLINE SkPicture* ToSkPicture(PaintRecord* record) {
+  return static_cast<SkPicture*>(record);
 }
 
-inline sk_sp<SkPicture> ToSkPicture(sk_sp<PaintRecord> record) {
-  return record;
+ALWAYS_INLINE sk_sp<SkPicture> ToSkPicture(sk_sp<PaintRecord> record) {
+  return sk_ref_sp(ToSkPicture(record.get()));
 }
 
-inline sk_sp<const SkPicture> ToSkPicture(sk_sp<const PaintRecord> record) {
-  return record;
+ALWAYS_INLINE sk_sp<const SkPicture> ToSkPicture(
+    sk_sp<const PaintRecord> record) {
+  return sk_ref_sp(ToSkPicture(record.get()));
 }
 
 }  // namespace cc
 
 #endif  // CC_PAINT_PAINT_RECORD_H_