Add SplitUVPlanes and MergeUVPlanes

source/convert_from_argb.cc

Index: source/convert_from_argb.cc
diff --git a/source/convert_from_argb.cc b/source/convert_from_argb.cc
index 2a8682b7eb42f17642d27ea5ff1cfd7759d4ddae..efc8e70f73ceceb229d3b5dc1040d396d5f37f4c 100644
--- a/source/convert_from_argb.cc
+++ b/source/convert_from_argb.cc
@@ -265,8 +265,7 @@ int ARGBToNV12(const uint8* src_argb, int src_stride_argb,
                       uint8* dst_u, uint8* dst_v, int width) = ARGBToUVRow_C;
   void (*ARGBToYRow)(const uint8* src_argb, uint8* dst_y, int width) =
       ARGBToYRow_C;
-  void (*MergeUVRow_)(const uint8* src_u, const uint8* src_v, uint8* dst_uv,
-                      int width) = MergeUVRow_C;
+  MergeUVRowFunction MergeUVRow_ = GetOptimizedMergeUVRowFunction(width);
   if (!src_argb ||
       !dst_y || !dst_uv ||
       width <= 0 || height == 0) {
@@ -314,30 +313,6 @@ int ARGBToNV12(const uint8* src_argb, int src_stride_argb,
     }
   }
 #endif
-#if defined(HAS_MERGEUVROW_SSE2)
-  if (TestCpuFlag(kCpuHasSSE2)) {
-    MergeUVRow_ = MergeUVRow_Any_SSE2;
-    if (IS_ALIGNED(halfwidth, 16)) {
-      MergeUVRow_ = MergeUVRow_SSE2;
-    }
-  }
-#endif
-#if defined(HAS_MERGEUVROW_AVX2)
-  if (TestCpuFlag(kCpuHasAVX2)) {
-    MergeUVRow_ = MergeUVRow_Any_AVX2;
-    if (IS_ALIGNED(halfwidth, 32)) {
-      MergeUVRow_ = MergeUVRow_AVX2;
-    }
-  }
-#endif
-#if defined(HAS_MERGEUVROW_NEON)
-  if (TestCpuFlag(kCpuHasNEON)) {
-    MergeUVRow_ = MergeUVRow_Any_NEON;
-    if (IS_ALIGNED(halfwidth, 16)) {
-      MergeUVRow_ = MergeUVRow_NEON;
-    }
-  }
-#endif
   {
     // Allocate a rows of uv.
     align_buffer_64(row_u, ((halfwidth + 31) & ~31) * 2);