[IndexedDB] Mojo testing harness.

content/browser/indexed_db/indexed_db_dispatcher_host.cc

Index: content/browser/indexed_db/indexed_db_dispatcher_host.cc
diff --git a/content/browser/indexed_db/indexed_db_dispatcher_host.cc b/content/browser/indexed_db/indexed_db_dispatcher_host.cc
index 2ecd7b18d642e4973abb93ff24a562a8ec218617..91d07ae88a9484bd853c8346320507cfb30cecbf 100644
--- a/content/browser/indexed_db/indexed_db_dispatcher_host.cc
+++ b/content/browser/indexed_db/indexed_db_dispatcher_host.cc
@@ -84,6 +84,7 @@ IndexedDBDispatcherHost::IndexedDBDispatcherHost(
                                           std::move(request_context_getter),
                                           indexed_db_context_)
                     : nullptr;
+  DCHECK(idb_helper_);
   DCHECK(indexed_db_context_.get());
 }