O Google publicou agora uma extensão oficial: " Voltar com Backspace ', para reativar o botão de retrocesso como a tecla de atalho para' voltar '.
Re-enables the backspace key as a back navigation button (except when writing text). Go back with the backspace button! This extension re-enables the backspace key as a back navigation button -- except if you're writing text.
Before Chrome 52, the backspace key navigated back (if you weren't writing text). Many people lost their progress while working online by accidentally pressing backspace and leaving a page -- so we removed the feature from Chrome, and created this extension for those who prefer the old behavior.
This extension can't restore backspace on certain special pages, for example any of the "chrome://" pages such as Settings or Extensions.
About the "all sites" permission: In order to capture backspace on every page, the extension needs to install a little piece of code on each one. It does nothing else with the the page, its information, or your typing.
Fonte: link