Pass args to SyncManager::Init via a struct.

sync/internal_api/public/sync_manager.cc

Index: sync/internal_api/public/sync_manager.cc
diff --git a/sync/internal_api/public/sync_manager.cc b/sync/internal_api/public/sync_manager.cc
index ec38b6c25ebf5fff3b2506d0c65451cab8628988..d2f9568c243f901d70f8c2509cecf8a669214745 100644
--- a/sync/internal_api/public/sync_manager.cc
+++ b/sync/internal_api/public/sync_manager.cc
@@ -16,6 +16,16 @@ SyncManager::ChangeObserver::~ChangeObserver() {}
 
 SyncManager::Observer::~Observer() {}
 
+SyncManager::InitArgs::InitArgs()
+    : extensions_activity(NULL),
+      change_delegate(NULL),
+      internal_components_factory(NULL),
+      encryptor(NULL),
+      cancelation_signal(NULL) {
+}
+
+SyncManager::InitArgs::~InitArgs() {}
+
 SyncManager::SyncManager() {}
 
 SyncManager::~SyncManager() {}