Make LevelDBObserver an associated interface to LevelDBWrapper.

content/browser/storage_partition_impl.cc

Index: content/browser/storage_partition_impl.cc
diff --git a/content/browser/storage_partition_impl.cc b/content/browser/storage_partition_impl.cc
index ba754b24d6269fd82bc2c6b47e00f50f4a3be11b..2c2b2f4b6f5b423c7ce6ab9b0501019e8e4918de 100644
--- a/content/browser/storage_partition_impl.cc
+++ b/content/browser/storage_partition_impl.cc
@@ -574,10 +574,8 @@ BroadcastChannelProvider* StoragePartitionImpl::GetBroadcastChannelProvider() {
 
 void StoragePartitionImpl::OpenLocalStorage(
     const url::Origin& origin,
-    mojom::LevelDBObserverPtr observer,
     mojo::InterfaceRequest<mojom::LevelDBWrapper> request) {
-  dom_storage_context_->OpenLocalStorage(
-      origin, std::move(observer), std::move(request));
+  dom_storage_context_->OpenLocalStorage(origin, std::move(request));
 }
 
 void StoragePartitionImpl::ClearDataImpl(