Lands http://codereview.chromium.org/99349 for Ryan....

media/base/yuv_convert.cc

 // Copyright (c) 2009 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
 // excerpt from wiki:
 //   These formulae are based on the NTSC standard;
@@ skipping 59 matching lines @@
 #ifdef _DEBUG
 #include "base/logging.h"
 #else
 #define DCHECK(a)
 #endif
 
 // MMX for Windows, Linux and Mac.
 // C++ code provided as a fall back.
 // Compile with /DUSE_MMX=0
 #ifndef USE_MMX
+
+#ifdef ARCH_CPU_ARM_FAMILY
+#define USE_MMX 0
+#else
 #define USE_MMX 1
 #endif
+#endif
 
 namespace media {
 
 #if USE_MMX
 
 #define RGBY(i) { \
   static_cast<int16>(1.164 * 64 * (i - 16) + 0.5), \
   static_cast<int16>(1.164 * 64 * (i - 16) + 0.5), \
   static_cast<int16>(1.164 * 64 * (i - 16) + 0.5), \
   0 \
@@ skipping 571 matching lines @@
                                              (clip(C298b + cr) << 16) |
                                              0xff000000;
 
     rgb_buf += 8;  // Advance 2 pixels.
   }
 }
 #endif
 
 
 }  // namespace media
-