Google Drive is Google's file sync app that lets you store all of your files online alongside your Google Docs documents, and keep them synced with all of your devices.
Give reviewers the current brief with each campaign asset.
Your reviewers see the brief beside the asset, with the brand decision they need to make clearly stated.
Attach the latest creative file for the brand review handoff.
Your brand reviewer gets the current campaign draft and the decision needed together on the review task.