Delete deprecated synced notifications code

Synced notifications no longer have native code. Delete the remaining code
(which has not been used for serveral milestones).

BUG=439577
[email protected], [email protected], [email protected]
[email protected]

Review URL: https://codereview.chromium.org/780363003

Cr-Commit-Position: refs/heads/master@{#307946}
diff --git a/extensions/browser/extension_function_histogram_value.h b/extensions/browser/extension_function_histogram_value.h
index 54f83ee..faa83c6 100644
--- a/extensions/browser/extension_function_histogram_value.h
+++ b/extensions/browser/extension_function_histogram_value.h
@@ -825,9 +825,9 @@
   DELETED_FILESYSTEMPROVIDERINTERNAL_OPENFILEREQUESTEDERROR,
   DELETED_FILESYSTEMPROVIDERINTERNAL_CLOSEFILEREQUESTEDSUCCESS,
   DELETED_FILESYSTEMPROVIDERINTERNAL_CLOSEFILEREQUESTEDERROR,
-  SYNCEDNOTIFICATIONSPRIVATE_GETINITIALDATA,
-  SYNCEDNOTIFICATIONSPRIVATE_UPDATENOTIFICATION,
-  SYNCEDNOTIFICATIONSPRIVATE_SETRENDERCONTEXT,
+  DELETED_SYNCEDNOTIFICATIONSPRIVATE_GETINITIALDATA,
+  DELETED_SYNCEDNOTIFICATIONSPRIVATE_UPDATENOTIFICATION,
+  DELETED_SYNCEDNOTIFICATIONSPRIVATE_SETRENDERCONTEXT,
   IDENTITY_GETACCOUNTS,
   FILEMANAGERPRIVATE_RESOLVEISOLATEDENTRIES,
   FILESYSTEMPROVIDERINTERNAL_READFILEREQUESTEDSUCCESS,