Back PaintRecord with PaintOpBuffer instead of SkPicture

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 "cc/paint/paint_export.h"
+#include "cc/paint/paint_op_buffer.h"
 #include "third_party/skia/include/core/SkPicture.h"
 
 namespace cc {
 
-using PaintRecord = SkPicture;
+// TODO(enne): Don't want to rename the world for this.  Using these as the
+// same types for now prevents an extra allocation.  Probably PaintRecord
+// will become an interface in the future.
+using PaintRecord = PaintOpBuffer;
 
-inline sk_sp<SkPicture> ToSkPicture(sk_sp<PaintRecord> record) {
-  return record;
-}
+// TODO(enne): Remove these if possible, they are really expensive.
+CC_PAINT_EXPORT sk_sp<SkPicture> ToSkPicture(sk_sp<PaintRecord> record);
 
-inline sk_sp<const SkPicture> ToSkPicture(sk_sp<const PaintRecord> record) {
-  return record;
-}
+CC_PAINT_EXPORT sk_sp<const SkPicture> ToSkPicture(
+    sk_sp<const PaintRecord> record);
 
 }  // namespace cc
 
 #endif  // CC_PAINT_PAINT_RECORD_H_