Reland: Add ETC1 powered SSE encoder for tile texture compression

cc/resources/texture_compressor.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 <stdio.h>

[reveman, 2015/05/05 15:30:11]

what is this for?

+
+#include "base/cpu.h"
 #include "base/logging.h"
 #include "cc/resources/texture_compressor_etc1.h"
+#include "cc/resources/texture_compressor_etc1_sse.h"
 
 namespace cc {
 
 scoped_ptr<TextureCompressor> TextureCompressor::Create(Format format) {
   switch (format) {
-    case kFormatETC1:
+    case kFormatETC1: {
+#if defined(__i386__) || defined(__x86_x64__)

[reveman, 2015/05/05 15:30:10]

can we remove this ifdef an just rely on base::CPU::has_sse2 always returning
the right thing?

+      base::CPU cpu;
+      if (cpu.has_sse2()) {
+        return make_scoped_ptr(new TextureCompressorETC1SSE());
+      }
+#endif
       return make_scoped_ptr(new TextureCompressorETC1());
+    }
+    default:

[reveman, 2015/05/05 15:30:11]

please avoid having a default case so the compiler will remind us of updating
this code when adding new formats

+      NOTREACHED();
+      return nullptr;
   }
-
-  NOTREACHED();
-  return nullptr;
 }
 
 }  // namespace cc