Add SSE optimizations to SincResampler.

media/base/sinc_resampler.h

Index: media/base/sinc_resampler.h
diff --git a/media/base/sinc_resampler.h b/media/base/sinc_resampler.h
index 58f5c2dd7ebf0c16886c7b9a958571b164d48139..ac5a07491a924fbb1750294b1286983cae3b88c5 100644
--- a/media/base/sinc_resampler.h
+++ b/media/base/sinc_resampler.h
@@ -6,7 +6,9 @@
 #define MEDIA_BASE_SINC_RESAMPLER_H_
 
 #include "base/callback.h"
+#include "base/gtest_prod_util.h"
 #include "base/memory/scoped_ptr.h"
+#include "build/build_config.h"
 #include "media/base/media_export.h"
 
 namespace media {
@@ -33,8 +35,24 @@ class MEDIA_EXPORT SincResampler {
   int ChunkSize();
 
  private:
+  FRIEND_TEST_ALL_PREFIXES(SincResamplerTest, Convolve);
+  FRIEND_TEST_ALL_PREFIXES(SincResamplerTest, ConvolveBenchmark);
+
   void InitializeKernel();
 
+  // Compute convolution of |k1| and |k2| over |input_ptr|, resultant sums are
+  // linearly interpolated using |kernel_interpolation_factor|.  The underlying
+  // implementation is chosen at run time based on SSE support.
+  static float Convolve(const float* input_ptr, const float* k1,
+                        const float* k2, double kernel_interpolation_factor);
+  static float Convolve_C(const float* input_ptr, const float* k1,
+                          const float* k2, double kernel_interpolation_factor);
+#if defined(ARCH_CPU_X86_FAMILY) && defined(__SSE__)

[Ami GONE FROM CHROMIUM, 2012/07/21 17:25:10]

#if unnecessary (fine to leave methods undefined as long as you don't use them).

[DaleCurtis, 2012/07/24 00:13:07]

Done.

+  static float Convolve_SSE(const float* input_ptr, const float* k1,
+                            const float* k2,
+                            double kernel_interpolation_factor);
+#endif
+
   // The ratio of input / output sample rates.
   double io_sample_rate_ratio_;