Support HTML5 / Javascript chunked file uploads
Summary:
Ref T7149. This adds chunking support to drag-and-drop uploads. It never activates right now unless you hack things up, since the chunk engine is still hard-coded as disabled.
The overall approach is the same as arc upload in D12061, with some slight changes to the API return values to avoid a few extra HTTP calls.
Test Plan:
- Enabled chunk engine.
- Uploaded some READMEs in a bunch of tiny 32 byte chunks.
- Worked out of the box in Safari, Chrome, Firefox.
Reviewers: btrahan
Reviewed By: btrahan
Subscribers: epriestley
Maniphest Tasks: T7149
Differential Revision: https://secure.phabricator.com/D12066