Issue Summary

The PR has a mark file as viewed checkbox for each file in the PR. If you check them and refresh the page, the files that were marked as viewed gets reset. 

Steps to Reproduce

1. Open a PR with 1 or more files
2. Click on "Mark file as viewed" checkbox for any number of files
3. Refresh the page

Expected Results

The files that were marked as viewed will still be marked as viewed on page refresh. 

Actual Results

The files are not marked as viewed after refresh. It resets to 0 files viewed

Workaround

Uncheck Whitespace from File Changes -> Settings -> Show Whitespace Changes

This will make the Mark File as viewed persist across browser refreshes