Change userid from a uint32_t to a string guid

media/mojo/services/mojo_media_application.h

Index: media/mojo/services/mojo_media_application.h
diff --git a/media/mojo/services/mojo_media_application.h b/media/mojo/services/mojo_media_application.h
index cd5f80371dadc0013bcd5bc42b16ea5dffdeb94a..9844ab135421d1fcbcf0789f1c4f0ef6122fd0b2 100644
--- a/media/mojo/services/mojo_media_application.h
+++ b/media/mojo/services/mojo_media_application.h
@@ -29,8 +29,8 @@ class MojoMediaApplication
   // mojo::ShellClient implementation.
   void Initialize(mojo::Connector* connector,
                   const std::string& url,
-                  uint32_t id,
-                  uint32_t user_id) final;
+                  const std::string& user_id,
+                  uint32_t id) final;
   bool AcceptConnection(mojo::Connection* connection) final;
 
   // mojo::InterfaceFactory<interfaces::ServiceFactory> implementation.