Add texture compression interface and ETC1 encoder.

cc/resources/texture_compressor_etc1.h

+// Copyright 2015 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_RESOURCES_TEXTURE_COMPRESSOR_ETC1_H_
+#define CC_RESOURCES_TEXTURE_COMPRESSOR_ETC1_H_
+
+#include "cc/resources/texture_compressor.h"
+
+namespace cc {
+
+class CC_EXPORT TextureCompressorETC1 : public TextureCompressor {
+ public:
+  TextureCompressorETC1() {}
+
+  // Compress a texture using ETC1. Note that the |quality| parameter is
+  // ignored. The current implementation does not support different quality
+  // settings.
+  void Compress(const uint8_t* src,
+                uint8_t* dst,
+                int width,
+                int height,
+                Quality quality) override;
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(TextureCompressorETC1);
+};
+
+}  // namespace cc
+
+#endif  // CC_RESOURCES_TEXTURE_COMPRESSOR_ETC1_H_