cleanup: remove unnecessary ignoreContentType field (#2715)

internal/transport/http2_client.go

@@ -1152,10 +1152,7 @@ func (t *http2Client) operateHeaders(frame *http2.MetaHeadersFrame) {
 		return
 	}
 
-	state := &decodeState{
-		serverSide:        false,
-		ignoreContentType: !initialHeader,
-	}
+	state := &decodeState{}
 	// Initialize isGRPC value to be !initialHeader, since if a gRPC ResponseHeader has been received
 	// which indicates peer speaking gRPC, we are in gRPC mode.
 	state.data.isGRPC = !initialHeader

internal/transport/http2_server.go

@@ -287,8 +287,7 @@ func newHTTP2Server(conn net.Conn, config *ServerConfig) (_ ServerTransport, err
 func (t *http2Server) operateHeaders(frame *http2.MetaHeadersFrame, handle func(*Stream), traceCtx func(context.Context, string) context.Context) (fatal bool) {
 	streamID := frame.Header().StreamID
 	state := &decodeState{
-		serverSide:        true,
-		ignoreContentType: false,
+		serverSide: true,
 	}
 	if err := state.decodeHeader(frame); err != nil {
 		if se, ok := status.FromError(err); ok {

internal/transport/http_util.go

@@ -139,14 +139,6 @@ type parsedHeaderData struct {
 type decodeState struct {
 	// whether decoding on server side or not
 	serverSide bool
-	// ignoreContentType indicates whether when processing the HEADERS frame, ignoring checking the
-	// content-type is grpc or not.
-	//
-	// Trailers (after headers) should not have a content-type. And thus we will ignore checking the
-	// content-type.
-	//
-	// For server, this field is always false.
-	ignoreContentType bool
 
 	// Records the states during HPACK decoding. It will be filled with info parsed from HTTP HEADERS
 	// frame once decodeHeader function has been invoked and returned.