This is one much needed improvement for the integration between Android and Chrome OS. Having the files read-only from the Chrome OS side pretty much makes it useless though. Hope this will be fixed before the integration moves to the stable channel, otherwise it will result in lots of user confusion.
Images, videos and audio files from Android apps are now accessible from the Files app in the latest Dev update of Chrome OS.

Think of it as a semi-flattened view of all media files kept tracked by Android. Note that these files are read-only.

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