Google told us no more support for SPDY. Ttransitioning from SPDY to HTTP/2
Add "http2" to your nginx.conf file.
If you got an error msg just like 「ERR_SPDY_INADEQUATE_TRANSPORT_SECURITY」, plz check the config file below here. 　　

ssl_protocols TLSv1 TLSv1.1 TLSv1.2;
ssl_ciphers EECDH+CHACHA20:EECDH+AES128:RSA+AES128:EECDH+AES256:RSA+AES256:EECDH+3DES:RSA+3DES:!MD5;
ssl_prefer_server_ciphers on;