Replace EncodeBitmap with an interface.

include/core/SkPixelSerializer.h

+/*
+ * Copyright 2014 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#ifndef SkPixelSerializer_DEFINED
+#define SkPixelSerializer_DEFINED
+
+#include "SkRefCnt.h"
+
+class SkData;
+struct SkImageInfo;
+
+/**
+ *  Interface for serializing pixels, e.g. SkBitmaps in an SkPicture.
+ */
+class SkPixelSerializer : public SkRefCnt {
+public:
+    virtual ~SkPixelSerializer() {}
+
+    /**
+     *  Call to determine if the client wants to serialize the encoded data. If
+     *  false, serialize another version (e.g. the result of encodePixels).
+     */
+    bool useEncodedData(const void* data, size_t len) {
+        return this->onUseEncodedData(data, len);
+    }
+
+    /**
+     *  Call to get the client's version of encoding these pixels. If it
+     *  returns NULL, serialize the raw pixels.
+     */
+    SkData* encodePixels(const SkImageInfo& info, void* pixels, size_t rowBytes) {
+        return this->onEncodePixels(info, pixels, rowBytes);
+    }
+
+protected:
+    /**
+     *  Return true if you want to serialize the encoded data, false if you want
+     *  another version serialized (e.g. the result of encodePixels).
+     */
+    virtual bool onUseEncodedData(const void* data, size_t len) = 0;
+
+    /**
+     *  If you want to encode these pixels, return the encoded data as an SkData
+     *  Return null if you want to serialize the raw pixels.
+     */
+    virtual SkData* onEncodePixels(const SkImageInfo&, void* pixels, size_t rowBytes) = 0;
+};
+#endif // SkPixelSerializer_DEFINED