Re-add metric API

[zhongnansu]

Issue #, if available:

Description of changes:
Add the frontend metric API back, since we accidentally disabled it in last commit

By submitting this pull request, I confirm that you can use, modify, copy, and redistribute this contribution, under the terms of your choice.

[codecov]

Codecov Report

Merging #303 (8e7b80a) into 7.9.1 (758f432) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##            7.9.1     #303   +/-   ##
=======================================
  Coverage   72.96%   72.96%           
=======================================
  Files          32       32           
  Lines        1809     1809           
  Branches      354      354           
=======================================
  Hits         1320     1320           
  Misses        484      484           
  Partials        5        5           

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update 758f432...8e7b80a. Read the comment docs.