Unfortunately, it reproduced on M67 stable too...

To pass CTS, ArcFileSystemService and ArcIntentHelper are running in different UID now.
Due to this change, ArcIntentHelper lost a permission to access media files in MediaDocumentsProvider, since only one UI can have the permission and ArcFileSystemService has it.

This explain the current symptom, and a possible workaround is that modifying ArcIntentHelper to directly access MediaProvider instead of MediaDocumentsProvider by generating media URLs.
I'll try this workaround.

According to nya@, reverting the change will be dangerous.
I'm going to make a fix and merge it to M68, since M67 is already stable for a while.
+weifangsun@ for double check about schedule for the fix.

Thanks Fukino-san for catching this issue. It's bad I did not notice this earlier...

After offline discussion, I got an idea of another approach. The problem here is not specific to MediaDocumentsProvider but other DocumentsProviders will be also affected (we don't query them yet, but will face the same issue in the future). So another approach would be to allow ArcIntentHelper to obtain permission to any DocumentsProvider URIs from ArcFileSystemService by some means, e.g. sending intents.

Thanks for looping me in fukino@!

I agree that merging back to M67 seems risky. Let's test the fix out on M68 first. Quick question - Do the updates in M69 to make the Android files locally available change this interaction or is it unrelated?

Re:#5
The updates in M69 is unrelated to this issue.
This issue still reproduces with the same repro steps on ToT.

fukino@ - Just checking, I think this is the same as b/111288986 which is now Fixed?

Yes, b/111288986 is the counter part of this issue and it is fixed now on M68+.