Many Google Chrome features aren’t enabled by default because they’re not ready for primetime or they’re too advanced. Unfortunately, you can’t enable them from the interface and you have use command-line flags.
A recent Chromium build added a new internal page that lets you enable some advanced features: about:labs.
“Tabpose is currently the only lab on Mac, tabs-on-left the only lab on Windows. about:labs should not be visible on the stable channel. Labs that were enabled on the dev channel should not be enabled on the stable channel.”
Both features can also be enabled by adding command-line flags to a Chrome shortcut: –enable-vertical-tabs for side tabs and –enable-expose-for-tabs for tabposé. After enabling vertical tabs using the command-line flag, right-click on a tab and select “use side tabs”.