Add texture compression utility

src/utils/SkTextureCompressor.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 SkTextureCompressor_DEFINED
+#define SkTextureCompressor_DEFINED
+
+class SkBitmap;
+class SkData;
+
+namespace SkTextureCompressor {
+    // Various texture compression formats that we support.
+    enum Format {
+        // Alpha only format.
+        kLATC_Format,
+
+        kLast_Format = kLATC_Format
+    };
+    static const int kFormatCnt = kLast_Format + 1;
+
+    // Returns an SkData holding a blob of compressed data that corresponds
+    // to the bitmap. If the bitmap colorType cannot be compressed using the 
+    // associated format, then we return NULL. The caller is responsible for
+    // calling unref() on the returned data.
+    SkData* CompressBitmapToFormat(const SkBitmap& bitmap, Format format);
+}
+
+#endif