Is it possible to get the browser keys? If yes, is it possible to decrypt the traffic?
For SSL connections, browser helps you to do the handshakes (including the key-exchanging, see: https://www.ibm.com/support/knowledgecenter/en/SSFKSJ_7.1.0/com.ibm.mq.doc/sy10660_.htm ) and thus processes the keys, for the encryption and decryption of the following data transmission, of course. When debugging, browser could apply the keys to decrypt the traffic for you.
However, for wireshark, the msg of SSL handshakes might be caught, but hard to ensure. I think this is why wireshark do not provide traffic decryption, by default. Moreover, if you could trace the handshakes messages munally, you can find the keys and apply them for the traffic decryption.