We have launched a new UI for all Google Drive pickers–the interface that allows people to select and insert content stored in Google Drive (e.g. Insert files from Drive, Insert Images from Drive, etc). The UI will closely align with the new Google Drive UI, and will move all menu options from vertical tabs on the left side of the picker to horizontal tabs running along the top of the picker.
Rapid release and Scheduled release (gradual rollout)
Reference by : www.google.com