Transfer files from dropbox/drive to Google cloud storage : <p>We are planning to implement a feature to let customers browse their images in their own google drive or dropbox accounts (within our app), and select ones they wanna use in our app. Then, we will save these images into our Google cloud storage (GCS) place.</p>

<p>A simple approach is to use OAuth to download the customers' images from dropbox/drive to our local disk, then upload them to our GCS.</p>

<p>I am wondering if it is possible to make a direct transfer between dropbox/drive and GCS? GCS does provide <a href="https://cloud.google.com/storage/transfer/" rel="noreferrer">transfer service</a> for S3. You can also create a list of URL list, but each URL needs to be publicly accessible, which in our case does not seem possible.</p>

<p>Is there any better suggestion on how to implement this feature? Thanks</p>
