Introduce the plumbing necessary to report Unrecoverable error from model safe workers.

chrome/browser/sync/engine/sync_scheduler.cc

Index: chrome/browser/sync/engine/sync_scheduler.cc
diff --git a/chrome/browser/sync/engine/sync_scheduler.cc b/chrome/browser/sync/engine/sync_scheduler.cc
index f4aa2a01a6438be05e67f573a11c7f0c005f4c19..f4015e61708b6c3a3596174099b6b7d5ea7cb546 100644
--- a/chrome/browser/sync/engine/sync_scheduler.cc
+++ b/chrome/browser/sync/engine/sync_scheduler.cc
@@ -1165,6 +1165,13 @@ void SyncScheduler::OnSyncProtocolError(
     OnActionableError(snapshot);
 }
 
+void SyncScheduler::OnUnrecoverableError(
+    const tracked_objects::Location& from_here,
+    const std :: string& message) {
+  syncer_->RequestEarlyExit();
+  SyncEngineEvent event(from_here, message);
+  session_context_->NotifyListeners(event);
+}
 
 void SyncScheduler::OnServerConnectionEvent(
     const ServerConnectionEvent& event) {