I frequently use the overrides tab in Chrome Developer tools to emulate other device such IPhone and IPad, but after upgrading to last version (32.0.1700.76 m) everything in the overrides tab is gone and replaced by a checkbox saying "Show 'Emulation' view in console drawer".
Checking this checkbox does not enable a 'Emulation' view in the Console drawer. The "Show Console" button seems to be disabled.
See here for more information.
Before starting open the dev tools console (on a Mac cmd-option-i)
There is also a note in the link above stating:
Note: Emulation tools within DevTools were previously contained within an Overrides pane inside the Settings panel. The Emulation panel is the new Overrides pane.