Doc contents are added only after the tracking has been setup.
All read paths on the tracking have been checked to gracefully handle
the case of existing doc_id but missing doc contents.
- getDoc: -1 operation
REF: 0a2b47c660c60b95e360d8f3b3e30b862ceb6d79
These changes were previously merged, not deployed, and reverted. This
reverts the revert.
This reverts commit a6b8c6c658b33b6eee78b8b99e43308f32211ae2, reversing
changes made to 93c98921372eed4244d22fce800716cb27eca299.