Just received this note from ESRI – we will be monitoring this, but please let us know if there are any issues, especially with some of the javascript based applications that we deploy.
Google started pushing out Chrome 51 earlier today including a change that breaks many apps built on the ArcGIS API for Javascript v3.8 – 3.16 including most notably the “home app” in ArcGIS Online and all Portal for ArcGIS version from 10.3 through 10.4.1
While we are working directly with Google to see if the change in question can be reverted before Chrome 51 is too widely distributed, we are also preparing patches for all affected products and apps.
Because most Chrome users auto-update this has the potential to have far-reaching and immediate consequences.