Change userid from a uint32_t to a string guid

components/leveldb/leveldb_app.h

Index: components/leveldb/leveldb_app.h
diff --git a/components/leveldb/leveldb_app.h b/components/leveldb/leveldb_app.h
index d9877d95b3957e80303bec62efe98f226686c5b4..886f3491564e70619402127eb72f179ddef0a8fd 100644
--- a/components/leveldb/leveldb_app.h
+++ b/components/leveldb/leveldb_app.h
@@ -23,8 +23,8 @@ class LevelDBApp : public mojo::ShellClient,
   // |ShellClient| override:
   void Initialize(mojo::Connector* connector,
                   const std::string& url,
-                  uint32_t id,
-                  uint32_t user_id) override;
+                  const std::string& user_id,
+                  uint32_t id) override;
   bool AcceptConnection(mojo::Connection* connection) override;
 
   // TODO(erg): What do we have to do on shell error?