[iOS] Upstream observer bridges

ios/chrome/browser/sync/sync_observer_bridge.mm

+// Copyright 2012 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include "ios/chrome/browser/sync/sync_observer_bridge.h"
+
+#include "base/logging.h"
+#include "components/sync_driver/sync_service.h"
+
+SyncObserverBridge::SyncObserverBridge(id<SyncObserverModelBridge> delegate,
+                                       sync_driver::SyncService* sync_service)
+    : delegate_(delegate), scoped_observer_(this) {
+  DCHECK(delegate);
+  if (sync_service)
+    scoped_observer_.Add(sync_service);
+}
+
+SyncObserverBridge::~SyncObserverBridge() {
+}
+
+void SyncObserverBridge::OnStateChanged() {
+  [delegate_ onSyncStateChanged];
+}