DefaultDownloadDirectory setting applies to files being downloaded from the network.

Here the actual request is an option to have the image files, which are saved locally from the Camera application to the Downloads folder, to sync with Google Drive.

So I renamed the title.

Hi Stuart,
Is the behavior (only downloaded files synced to google drive, locally saved files not synced) expected? Could we change that?

What's the feature request here? 

Why doesn't the camera write the files to the DefaultDownloadDirectory, which could be in Google Drive or could be local depending on what the user has selected?

If I understand correctly, the DefaultDownloadDirectory is Downloads/ and camera app does save photos to Downloads/. The problem is that even though the user has configured that DefaultDownloadDirectory should be synced to Google Drive, only the real "downloaded" files are synced, those files locally saved to Downloads/ (such as those produced by camera app) are not synced. 

The feature request is to sync those locally saved files to Google Drive in the above case.

Users don't configure Downloads/ to sync to Google Drive, then just set their default download directory to a location within Google Drive, which is then honored by chrome when downloading.

Writing any files into Download/ does not sync them to drive automatically even if the download directory is pointing into drive.

I think you need to consider a more holistic approach to users configuring where their photos are stored both on the device and in the cloud - most likely this bug should be closed in favor of working that out.