Delete variations::CHROME_SYNC_EVENT_LOGGER

This existed to support recording of field trials as Sync user events.
That feature was abandoned and recently deleted (crrev.com/c/1557020).

Bug: 934762
Change-Id: Ic6deed6a5e951dac9e33e7e6891f92b76161a910
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/1556805
Reviewed-by: Steven Holte <[email protected]>
Commit-Queue: Marc Treib <[email protected]>
Cr-Commit-Position: refs/heads/master@{#649427}
diff --git a/components/variations/variations_http_header_provider.cc b/components/variations/variations_http_header_provider.cc
index 6865ef24..24c43fc 100644
--- a/components/variations/variations_http_header_provider.cc
+++ b/components/variations/variations_http_header_provider.cc
@@ -264,10 +264,9 @@
       case GOOGLE_WEB_PROPERTIES_TRIGGER:
         proto.add_trigger_variation_id(entry.first);
         break;
-      case CHROME_SYNC_EVENT_LOGGER:
       case ID_COLLECTION_COUNT:
-        // These cases included to get full enum coverage for switch, so that
-        // new enums introduce compiler warnings. Nothing to do for these.
+        // This case included to get full enum coverage for switch, so that
+        // new enums introduce compiler warnings. Nothing to do for this.
         break;
     }
   }