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/components_strings.grd b/components/components_strings.grd
index 06d62e1..4dd5fde 100644
--- a/components/components_strings.grd
+++ b/components/components_strings.grd
@@ -206,6 +206,7 @@
       <part file="find_in_page_strings.grdp" />
       <part file="history_strings.grdp" />
       <part file="login_dialog_strings.grdp" />
+      <part file="media_message_center_strings.grdp" />
       <part file="new_or_sad_tab_strings.grdp" />
       <part file="ntp_snippets_strings.grdp" />
       <part file="ntp_tiles_strings.grdp" />