Reland: Add ETC1 powered SSE encoder for tile texture compression

cc/resources/texture_compressor_etc1_unittest.cc

+// 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.
+
+#include "cc/resources/texture_compressor.h"
+
+#include "cc/base/util.h"
+#include "testing/gtest/include/gtest/gtest.h"
+
+namespace cc {
+namespace {
+
+const int kImageWidth = 256;
+const int kImageHeight = 256;
+const int kImageChannels = 4;
+const int kImageSizeInBytes = kImageWidth * kImageHeight * kImageChannels;
+
+TEST(TextureCompressorETC1Test, Compress256x256Ratio) {
+  scoped_ptr<TextureCompressor> compressor =
+      TextureCompressor::Create(TextureCompressor::kFormatETC1);
+  uint8_t src[kImageSizeInBytes];
+  uint8_t dst[kImageSizeInBytes];
+  const unsigned int kImagePoison = 0xDEADBEEF;
+
+  // Poison destination bytes so we can see how much has been
+  // overwritten by compression algorithm.
+  uint32_t* dst_32 = reinterpret_cast<uint32_t*>(dst);
+  for (int i = 0; i < kImageWidth * kImageHeight; i++) {
+    dst_32[i] = kImagePoison;
+  }
+
+  // Generate test texture.
+  for (int i = 0; i < kImageSizeInBytes; i++) {
+    src[i] = i % 256;
+  }
+
+  compressor->Compress(src, dst, kImageWidth, kImageHeight,
+                       TextureCompressor::kQualityLow);
+
+  int compressed_size = 0;
+  for (compressed_size = 0; compressed_size < kImageWidth * kImageHeight;
+       compressed_size++) {
+    if (dst_32[compressed_size] == kImagePoison) {
+      // Represents size in bytes of the compressed block.
+      compressed_size = compressed_size * 4;
+      break;
+    }
+  }
+
+  // Check if compression ratio is 8:1 for RGBA or BGRA images, after discarding
+  // alpha channel.
+  EXPECT_EQ(kImageSizeInBytes, compressed_size * 8);
+}
+
+}  // namespace
+}  // namespace cc