Revert of Cleanup: Remove unneeded SSE2 checks and unused code.

media/base/simd/convert_yuv_to_rgb_x86.cc

Index: media/base/simd/convert_yuv_to_rgb_x86.cc
diff --git a/media/base/simd/convert_yuv_to_rgb_x86.cc b/media/base/simd/convert_yuv_to_rgb_x86.cc
index 2e6f5e30ab0f57518dcbaba852e9b56c3715eab0..969890dbbefd386e0754d19c24e00000b52d44f0 100644
--- a/media/base/simd/convert_yuv_to_rgb_x86.cc
+++ b/media/base/simd/convert_yuv_to_rgb_x86.cc
@@ -13,6 +13,34 @@
 #include "media/base/yuv_convert.h"
 
 namespace media {
+
+void ConvertYUVToRGB32_MMX(const uint8* yplane,
+                           const uint8* uplane,
+                           const uint8* vplane,
+                           uint8* rgbframe,
+                           int width,
+                           int height,
+                           int ystride,
+                           int uvstride,
+                           int rgbstride,
+                           YUVType yuv_type) {
+  unsigned int y_shift = GetVerticalShift(yuv_type);
+  for (int y = 0; y < height; ++y) {
+    uint8* rgb_row = rgbframe + y * rgbstride;
+    const uint8* y_ptr = yplane + y * ystride;
+    const uint8* u_ptr = uplane + (y >> y_shift) * uvstride;
+    const uint8* v_ptr = vplane + (y >> y_shift) * uvstride;
+
+    ConvertYUVToRGB32Row_MMX(y_ptr,
+                             u_ptr,
+                             v_ptr,
+                             rgb_row,
+                             width,
+                             GetLookupTable(yuv_type));
+  }
+
+  EmptyRegisterState();
+}
 
 void ConvertYUVAToARGB_MMX(const uint8* yplane,
                            const uint8* uplane,