Allow MediaMetrics entries from MediaParser

- Make MediaMetrcis stable C API visible to the media mainline module.
- Allow-list MediaMetrics entries from MediaParser.

Bug: 158742256
Test: Manual.
Change-Id: Icca73a9396195d8cf299eb03bc778a032aacc364
Merged-In: Icca73a9396195d8cf299eb03bc778a032aacc364
(cherry picked from commit 49fb4521427825e4d443260d6395446536f778cc)
2 files changed