Delete media/base/yuv_convert and dependents. Prefer libyuv.

media/base/simd/scale_yuv_to_rgb_mmx.asm

-; Copyright (c) 2011 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 "third_party/x86inc/x86inc.asm"
-
-;
-; This file uses MMX instructions.
-;
-  SECTION_TEXT
-  CPU       MMX
-
-; Use movq to save the output.
-%define MOVQ movq
-
-; void ScaleYUVToRGB32Row_MMX(const uint8_t* y_buf,
-;                             const uint8_t* u_buf,
-;                             const uint8_t* v_buf,
-;                             uint8_t* rgb_buf,
-;                             ptrdiff_t width,
-;                             ptrdiff_t source_dx);
-;                             const int16_t* convert_table);
-%define SYMBOL ScaleYUVToRGB32Row_MMX
-%include "scale_yuv_to_rgb_mmx.inc"