NOTE: This doesn’t work anymore, it’s broken in Mojave, I’ve written an updated article here about the fix.
If you plug an Android phone into your computer the Photos app will open like it does with an iPhone, but it may not see the photos on your Android Phone. This happened to me on my Nexus 5X phone and I needed to give the phone permission to share the photos with my computer. It’s the same for any Android phone.
After you plug the Android phone into your Mac, swipe down notifications and there will be a notification telling you that your phone is charging from the computer. Click this notification.
Now select ‘Transfer Photos (PTP)’ to allow your OS X Photos app to upload the photos from your phone.