Add support for serializing/deserializing of SkDrawable

src/core/SkRecordedDrawable.h

+/*
+ * Copyright 2016 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#include "SkBBoxHierarchy.h"
+#include "SkDrawable.h"
+#include "SkRecord.h"
+#include "SkRecorder.h"
+
+class SkRecordedDrawable : public SkDrawable {
+public:
+    SkRecordedDrawable(SkRecord* record, SkBBoxHierarchy* bbh, SkDrawableList* drawableList,
+                       const SkRect& bounds, bool doSaveLayerInfo)
+        : fRecord(SkRef(record))
+        , fBBH(SkSafeRef(bbh))
+        , fDrawableList(drawableList)   // we take ownership
+        , fBounds(bounds)
+        , fDoSaveLayerInfo(doSaveLayerInfo)
+    {}
+
+    void flatten(SkWriteBuffer& buffer) const override;
+
+    static sk_sp<SkFlattenable> CreateProc(SkReadBuffer& buffer);
+
+    Factory getFactory() const override { return CreateProc; }
+
+protected:
+    SkRect onGetBounds() override { return fBounds; }
+
+    void onDraw(SkCanvas* canvas) override;
+
+    SkPicture* onNewPictureSnapshot() override;
+
+private:
+    SkAutoTUnref<SkRecord>          fRecord;
+    SkAutoTUnref<SkBBoxHierarchy>   fBBH;
+    SkAutoTDelete<SkDrawableList>   fDrawableList;
+    const SkRect                    fBounds;
+    const bool                      fDoSaveLayerInfo;
+};