Do not use assembly implementations of YUV conversions in MSan builds.

media/base/yuv_convert.cc

 // Copyright (c) 2012 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.
 
 // This webpage shows layout of YV12 and other YUV formats
 // http://www.fourcc.org/yuv.php
 // The actual conversion is best described here
 // http://en.wikipedia.org/wiki/YUV
 // An article on optimizing YUV conversion using tables instead of multiplies
 // http://lestourtereaux.free.fr/papers/data/yuvrgb.pdf
@@ skipping 114 matching lines @@
   g_filter_yuv_rows_proc_ = FilterYUVRows_C;
   g_convert_yuv_to_rgb32_row_proc_ = ConvertYUVToRGB32Row_C;
   g_scale_yuv_to_rgb32_row_proc_ = ScaleYUVToRGB32Row_C;
   g_linear_scale_yuv_to_rgb32_row_proc_ = LinearScaleYUVToRGB32Row_C;
   g_convert_rgb32_to_yuv_proc_ = ConvertRGB32ToYUV_C;
   g_convert_rgb24_to_yuv_proc_ = ConvertRGB24ToYUV_C;
   g_convert_yuv_to_rgb32_proc_ = ConvertYUVToRGB32_C;
   g_convert_yuva_to_argb_proc_ = ConvertYUVAToARGB_C;
   g_empty_register_state_proc_ = EmptyRegisterStateStub;
 
-#if defined(ARCH_CPU_X86_FAMILY)
+  // Assembly code confuses MemorySanitizer.
+#if defined(ARCH_CPU_X86_FAMILY) && !defined(MEMORY_SANITIZER)
   base::CPU cpu;
   if (cpu.has_mmx()) {
     g_convert_yuv_to_rgb32_row_proc_ = ConvertYUVToRGB32Row_MMX;
     g_scale_yuv_to_rgb32_row_proc_ = ScaleYUVToRGB32Row_MMX;
     g_convert_yuv_to_rgb32_proc_ = ConvertYUVToRGB32_MMX;
     g_convert_yuva_to_argb_proc_ = ConvertYUVAToARGB_MMX;
     g_linear_scale_yuv_to_rgb32_row_proc_ = LinearScaleYUVToRGB32Row_MMX;
 
 #if defined(MEDIA_MMX_INTRINSICS_AVAILABLE)
     g_filter_yuv_rows_proc_ = FilterYUVRows_MMX;
@@ skipping 499 matching lines @@
                                width,
                                height,
                                ystride,
                                uvstride,
                                astride,
                                rgbstride,
                                yuv_type);
 }
 
 }  // namespace media