I can confirm crashes with Gmail (and other sites) on siduction
$ apt-cache policy chromium
chromium:
Installiert: 54.0.2840.101-1
Installationskandidat: 54.0.2840.101-1
Versionstabelle:
*** 54.0.2840.101-1 500
500 http://httpredir.debian.org/debian unstable/main amd64 Packages
100 /var/lib/dpkg/status