Creating a new wrapper for gif decoder

src/codec/SkGifInterlaceIter.h

+/*
+ * Copyright 2015 The Android Open Source Project
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#include "SkTypes.h"
+
+/*
+ * Helper class to determine the destination y-values for interlaced gifs
+ */
+class SkGifInterlaceIter : SkNoncopyable {
+public:
+
+    explicit SkGifInterlaceIter(int32_t height);
+
+    /*
+     * Get the next destination y-value
+     */
+    int32_t nextY();
+
+private:
+
+    /*
+     * Updates the iterator to prepare the next y-value
+     */
+    void prepareY();
+
+    const int32_t fHeight;
+    int32_t        fCurrY;
+    int32_t        fDeltaY;
+    const uint8_t* fStartYPtr;
+    const uint8_t* fDeltaYPtr;
+};