remove closenotifier

Signed-off-by: David Wu <david.wu@docker.com>

context/http.go

@@ -104,18 +104,6 @@ func GetRequestID(ctx context.Context) string {
 // WithResponseWriter returns a new context and response writer that makes
 // interesting response statistics available within the context.
 func WithResponseWriter(ctx context.Context, w http.ResponseWriter) (context.Context, http.ResponseWriter) {
-	if closeNotifier, ok := w.(http.CloseNotifier); ok {
-		irwCN := &instrumentedResponseWriterCN{
-			instrumentedResponseWriter: instrumentedResponseWriter{
-				ResponseWriter: w,
-				Context:        ctx,
-			},
-			CloseNotifier: closeNotifier,
-		}
-
-		return irwCN, irwCN
-	}
-
 	irw := instrumentedResponseWriter{
 		ResponseWriter: w,
 		Context:        ctx,
@@ -270,14 +258,6 @@ func (ctx *muxVarsContext) Value(key interface{}) interface{} {
 	return ctx.Context.Value(key)
 }
 
-// instrumentedResponseWriterCN provides response writer information in a
-// context. It implements http.CloseNotifier so that users can detect
-// early disconnects.
-type instrumentedResponseWriterCN struct {
-	instrumentedResponseWriter
-	http.CloseNotifier
-}
-
 // instrumentedResponseWriter provides response writer information in a
 // context. This variant is only used in the case where CloseNotifier is not
 // implemented by the parent ResponseWriter.
@@ -355,13 +335,3 @@ func (irw *instrumentedResponseWriter) Value(key interface{}) interface{} {
 fallback:
 	return irw.Context.Value(key)
 }
-
-func (irw *instrumentedResponseWriterCN) Value(key interface{}) interface{} {
-	if keyStr, ok := key.(string); ok {
-		if keyStr == "http.response" {
-			return irw
-		}
-	}
-
-	return irw.instrumentedResponseWriter.Value(key)
-}