use NULL for default host in grpc_channel_call_create

src/csharp/Grpc.Core/Channel.cs

@@ -52,7 +52,6 @@ namespace Grpc.Core
         readonly GrpcEnvironment environment;
         readonly ChannelSafeHandle handle;
         readonly List<ChannelOption> options;
-        readonly string target;
         bool disposed;
 
         /// <summary>
@@ -81,7 +80,6 @@ namespace Grpc.Core
                     this.handle = ChannelSafeHandle.CreateInsecure(host, nativeChannelArgs);
                 }
             }
-            this.target = GetOverridenTarget(host, this.options);
         }
 
         /// <summary>
@@ -163,14 +161,6 @@ namespace Grpc.Core
             GC.SuppressFinalize(this);
         }
 
-        internal string Target
-        {
-            get
-            {
-                return target;
-            }
-        }
-
         internal ChannelSafeHandle Handle
         {
             get
@@ -225,26 +215,5 @@ namespace Grpc.Core
             // TODO(jtattermusch): it would be useful to also provide .NET/mono version.
             return string.Format("grpc-csharp/{0}", VersionInfo.CurrentVersion);
         }
-
-        /// <summary>
-        /// Look for SslTargetNameOverride option and return its value instead of originalTarget
-        /// if found.
-        /// </summary>
-        private static string GetOverridenTarget(string originalTarget, IEnumerable<ChannelOption> options)
-        {
-            if (options == null)
-            {
-                return originalTarget;
-            }
-            foreach (var option in options)
-            {
-                if (option.Type == ChannelOption.OptionType.String
-                    && option.Name == ChannelOptions.SslTargetNameOverride)
-                {
-                    return option.StringValue;
-                }
-            }
-            return originalTarget;
-        }
     }
 }

src/csharp/Grpc.Core/Internal/AsyncCall.cs

@@ -67,7 +67,7 @@ namespace Grpc.Core.Internal
         public void Initialize(Channel channel, CompletionQueueSafeHandle cq, string methodName, Timespec deadline)
         {
             this.channel = channel;
-            var call = channel.Handle.CreateCall(channel.CompletionRegistry, cq, methodName, channel.Target, deadline);
+            var call = channel.Handle.CreateCall(channel.CompletionRegistry, cq, methodName, null, deadline);
             channel.Environment.DebugStats.ActiveClientCalls.Increment();
             InitializeInternal(call);
         }