Change userid from a uint32_t to a string guid

components/leveldb/leveldb_app.cc

Index: components/leveldb/leveldb_app.cc
diff --git a/components/leveldb/leveldb_app.cc b/components/leveldb/leveldb_app.cc
index 952d4f38444632a1ee5b1167a305b235802e2526..3dfd509d73fcac0c2330733f307447e724dd0cc3 100644
--- a/components/leveldb/leveldb_app.cc
+++ b/components/leveldb/leveldb_app.cc
@@ -15,8 +15,8 @@ LevelDBApp::~LevelDBApp() {}
 
 void LevelDBApp::Initialize(mojo::Connector* connector,
                             const std::string& url,
-                            uint32_t id,
-                            uint32_t user_id) {
+                            const std::string& user_id,
+                            uint32_t id) {
   tracing_.Initialize(connector, url);
   service_.reset(new LevelDBServiceImpl);
 }