GMC: Move shared media notification code to components

This CL extracts the shared media notification code from ash/media into
components/media_message_center. This will allow chrome/browser to use
the media notification without depending on ash.

Bug: 959478
Change-Id: Ic5623441308691ec0842a50ac4355cde1a9d274a
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1648707
Reviewed-by: Scott Violet <[email protected]>
Reviewed-by: Becca Hughes <[email protected]>
Commit-Queue: Tommy Steimel <[email protected]>
Cr-Commit-Position: refs/heads/master@{#667151}
diff --git a/components/OWNERS b/components/OWNERS
index c3e984d..51fa197a 100644
--- a/components/OWNERS
+++ b/components/OWNERS
@@ -12,6 +12,7 @@
 per-file dom_distiller_strings.grdp=file://components/dom_distiller/OWNERS
 per-file error_page_strings.grdp=file://components/error_page/OWNERS
 per-file management_strings.grdp=file://docs/privacy/OWNERS
+per-file media_message_center_strings.grdp=file://components/media_message_center/OWNERS
 per-file ntp_snippets_strings.grdp=file://components/ntp_snippets/OWNERS
 per-file ntp_tiles_strings.grdp=file://components/ntp_tiles/OWNERS
 per-file omnibox_strings.grdp=file://components/omnibox/OWNERS