[CobaltService] Support not using internal logger

Change-Id: I2cd0776d328e810450925294b8ea89862a628b2d
diff --git a/src/public/cobalt_service.cc b/src/public/cobalt_service.cc
index 42242a5..624c801 100644
--- a/src/public/cobalt_service.cc
+++ b/src/public/cobalt_service.cc
@@ -132,6 +132,10 @@
 
 std::unique_ptr<logger::Logger> CobaltService::NewLogger(
     std::unique_ptr<logger::ProjectContext> project_context, bool include_internal_logger) {
+  if (project_context == nullptr) {
+    return nullptr;
+  }
+
   auto logger = include_internal_logger ? internal_logger_.get() : nullptr;
   if (undated_event_manager_) {
     return std::make_unique<logger::Logger>(std::move(project_context), &logger_encoder_,