React to string[] -> StringValues changes.

src/Microsoft.AspNet.HttpOverrides/HttpMethodOverrideMiddleware.cs

@@ -38,7 +38,7 @@ namespace Microsoft.AspNet.HttpOverrides
                 }
                 else
                 {
-                    var xHttpMethodOverrideValue = context.Request.Headers.Get(xHttpMethodOverride);
+                    var xHttpMethodOverrideValue = context.Request.Headers[xHttpMethodOverride];
                     if (!string.IsNullOrEmpty(xHttpMethodOverrideValue))
                     {
                         context.Request.Method = xHttpMethodOverrideValue;

src/Microsoft.AspNet.HttpOverrides/OverrideHeaderMiddleware.cs

@@ -32,7 +32,7 @@ namespace Microsoft.AspNet.HttpOverrides
             if ((_options.ForwardedOptions & ForwardedHeaders.XForwardedFor) != 0)
             {
                 var xForwardedForHeaderValue = context.Request.Headers.GetCommaSeparatedValues(XForwardedForHeaderName);
-                if (xForwardedForHeaderValue != null && xForwardedForHeaderValue.Count > 0)
+                if (xForwardedForHeaderValue != null && xForwardedForHeaderValue.Length > 0)
                 {
                     IPAddress ipFromHeader;
                     if (IPAddress.TryParse(xForwardedForHeaderValue[0], out ipFromHeader))
@@ -40,7 +40,7 @@ namespace Microsoft.AspNet.HttpOverrides
                         var remoteIPString = context.Connection.RemoteIpAddress?.ToString();
                         if (!string.IsNullOrEmpty(remoteIPString))
                         {
-                            context.Request.Headers.Set(XOriginalIPName, remoteIPString);
+                            context.Request.Headers[XOriginalIPName] = remoteIPString;
                         }
                         context.Connection.RemoteIpAddress = ipFromHeader;
                     }
@@ -49,13 +49,13 @@ namespace Microsoft.AspNet.HttpOverrides
 
             if ((_options.ForwardedOptions & ForwardedHeaders.XForwardedHost) != 0)
             {
-                var xForwardHostHeaderValue = context.Request.Headers.Get(XForwardedHostHeaderName);
+                var xForwardHostHeaderValue = context.Request.Headers[XForwardedHostHeaderName];
                 if (!string.IsNullOrEmpty(xForwardHostHeaderValue))
                 {
                     var hostString = context.Request.Host.ToString();
                     if (!string.IsNullOrEmpty(hostString))
                     {
-                        context.Request.Headers.Set(XOriginalHostName, hostString);
+                        context.Request.Headers[XOriginalHostName] = hostString;
                     }
                     context.Request.Host = HostString.FromUriComponent(xForwardHostHeaderValue);
                 }
@@ -63,12 +63,12 @@ namespace Microsoft.AspNet.HttpOverrides
 
             if ((_options.ForwardedOptions & ForwardedHeaders.XForwardedProto) != 0)
             {
-                var xForwardProtoHeaderValue = context.Request.Headers.Get(XForwardedProtoHeaderName);
+                var xForwardProtoHeaderValue = context.Request.Headers[XForwardedProtoHeaderName];
                 if (!string.IsNullOrEmpty(xForwardProtoHeaderValue))
                 {
                     if (!string.IsNullOrEmpty(context.Request.Scheme))
                     {
-                        context.Request.Headers.Set(XOriginalProtoName, context.Request.Scheme);
+                        context.Request.Headers[XOriginalProtoName] = context.Request.Scheme;
                     }
                     context.Request.Scheme = xForwardProtoHeaderValue;
                 }

src/Microsoft.AspNet.HttpOverrides/project.json

@@ -7,7 +7,7 @@
   },
   "dependencies": {
     "Microsoft.CSharp": "4.0.0-*",
-    "Microsoft.AspNet.Http.Abstractions": "1.0.0-*",
+    "Microsoft.AspNet.Http.Extensions": "1.0.0-*",
     "Microsoft.Framework.NotNullAttribute.Sources": { "version": "1.0.0-*", "type": "build" }
   },
   "frameworks": {