Add browser tests for clearing sync registrations with site data

content/browser/background_sync/background_sync_network_observer.h

Index: content/browser/background_sync/background_sync_network_observer.h
diff --git a/content/browser/background_sync/background_sync_network_observer.h b/content/browser/background_sync/background_sync_network_observer.h
index f00727c8cd6a90ddd4702459d5a48a516032e6ef..26700db4b519cc6dc690a8ca26fd191d4c7404d0 100644
--- a/content/browser/background_sync/background_sync_network_observer.h
+++ b/content/browser/background_sync/background_sync_network_observer.h
@@ -33,11 +33,11 @@ class CONTENT_EXPORT BackgroundSyncNetworkObserver
   void OnNetworkChanged(
       net::NetworkChangeNotifier::ConnectionType connection_type) override;
 
- private:
-  friend class BackgroundSyncBrowserTest;
-  friend class BackgroundSyncManagerTest;
-  friend class BackgroundSyncServiceImplTest;
+  // Allow tests to call NotifyManagerIfNetworkChanged.
+  void NotifyManagerIfNetworkChangedForTesting(
+      net::NetworkChangeNotifier::ConnectionType connection_type);
 
+ private:
   // Calls NotifyNetworkChanged if the connection type has changed.
   void NotifyManagerIfNetworkChanged(
       net::NetworkChangeNotifier::ConnectionType connection_type);