Shader error: Use of UNITY_MATRIX_MV is detected. To transform a vertex into view space, consider using UnityObjectToViewPos for better performance.

I copy this shader script from Google and it is error in Unity 2018. I need help from professional please.How to fix the error?

 Shader "Custom/Sprite_Billboard" {
      Properties
      {
          [PerRendererData] _MainTex ("Sprite Texture", 2D) = "white" {}
          _Color ("Tint", Color) = (1,1,1,1)
          //_Time ("Time", Float) = 0
          [MaterialToggle] PixelSnap ("Pixel snap", Float) = 0
      }
  
      SubShader
      {
          Tags
          { 
              "Queue"="Transparent"
              "SortingLayer"="Resources_Sprites" 
              "IgnoreProjector"="True" 
              "RenderType"="Transparent" 
              "PreviewType"="Plane"
              "CanUseSpriteAtlas"="True"
              "DisableBatching" = "True"
          }
  
          Cull Off
          Lighting Off
          ZWrite Off
          Blend One OneMinusSrcAlpha
  
          Pass
          {
          CGPROGRAM
              #pragma vertex vert
              #pragma fragment frag
              #pragma target 2.0
              #pragma multi_compile _ PIXELSNAP_ON
              #pragma multi_compile _ ETC1_EXTERNAL_ALPHA
              #include "UnityCG.cginc"
  
  //            uniform Float _Time;
  
              struct appdata_t
              {
                  float4 vertex   : POSITION;
                  float4 color    : COLOR;
                  float2 texcoord : TEXCOORD0;
                  UNITY_VERTEX_INPUT_INSTANCE_ID
              };
  
              struct v2f
              {
                  float4 vertex   : SV_POSITION;
                  fixed4 color    : COLOR;
                  float2 texcoord  : TEXCOORD0;
                  UNITY_VERTEX_OUTPUT_STEREO
              };
              
              fixed4 _Color;
  
              v2f vert(appdata_t IN)
              {
                  v2f OUT;
                  UNITY_SETUP_INSTANCE_ID(IN);
                  UNITY_INITIALIZE_VERTEX_OUTPUT_STEREO(OUT);
  //                OUT.vertex = UnityObjectToClipPos(IN.vertex);
                  OUT.texcoord = IN.texcoord;
                  OUT.color = IN.color * _Color;
              //    #ifdef PIXELSNAP_ON
  
                  OUT.vertex = mul(UNITY_MATRIX_P, 
                   mul(UNITY_MATRIX_MV, float4(0.0, 0.0, 0.0, 1.0))
                  - float4(IN.vertex.y, IN.vertex.x, 0.0, 0.0)
                   * float4(0.1, 0.1, 1.0, 1.0));
  
       //           OUT.vertex = UnityPixelSnap (OUT.vertex);
              //    #endif
  
                  return OUT;
              }
  
              sampler2D _MainTex;
              sampler2D _AlphaTex;
  
              fixed4 SampleSpriteTexture (float2 uv)
              {
                  fixed4 color = tex2D (_MainTex, uv);
  
  #if ETC1_EXTERNAL_ALPHA
                  // get the color from an external texture (usecase: Alpha support for ETC1 on android)
                  color.a = tex2D (_AlphaTex, uv).r;
  #endif //ETC1_EXTERNAL_ALPHA
  
                  return color;
              }
  
              fixed4 frag(v2f IN) : SV_Target
              {
                  fixed4 c = SampleSpriteTexture (IN.texcoord) * IN.color;
                  c.rgb *= c.a;
                  return c;
              }
          ENDCG
          }
      }
  }