libyuv::YUY2ToY for isolating Y channel of YUY2.

include/libyuv/planar_functions.h

 /*
  *  Copyright 2011 The LibYuv Project Authors. All rights reserved.
  *
  *  Use of this source code is governed by a BSD-style license
  *  that can be found in the LICENSE file in the root of the source
  *  tree. An additional intellectual property rights grant can be found
  *  in the file PATENTS. All contributing project authors may
  *  be found in the AUTHORS file in the root of the source tree.
  */
 
@@ skipping 93 matching lines @@
                uint8* dst_y, int dst_stride_y,
                uint8* dst_uv, int dst_stride_uv,
                int width, int height);
 
 LIBYUV_API
 int UYVYToNV12(const uint8* src_uyvy, int src_stride_uyvy,
                uint8* dst_y, int dst_stride_y,
                uint8* dst_uv, int dst_stride_uv,
                int width, int height);
 
+LIBYUV_API
+int YUY2ToY(const uint8* src_yuy2, int src_stride_yuy2,
+             uint8* dst_y, int dst_stride_y,
+             int width, int height);
+
 // Convert I420 to I400. (calls CopyPlane ignoring u/v).
 LIBYUV_API
 int I420ToI400(const uint8* src_y, int src_stride_y,
                const uint8* src_u, int src_stride_u,
                const uint8* src_v, int src_stride_v,
                uint8* dst_y, int dst_stride_y,
                int width, int height);
 
 // Alias
 #define J420ToJ400 I420ToI400
@@ skipping 396 matching lines @@
 int ARGBSobelXY(const uint8* src_argb, int src_stride_argb,
                 uint8* dst_argb, int dst_stride_argb,
                 int width, int height);
 
 #ifdef __cplusplus
 }  // extern "C"
 }  // namespace libyuv
 #endif
 
 #endif  // INCLUDE_LIBYUV_PLANAR_FUNCTIONS_H_