Add a instance groups to Connect(), and introduce an Identity struct.

components/filesystem/file_system_app.h

Index: components/filesystem/file_system_app.h
diff --git a/components/filesystem/file_system_app.h b/components/filesystem/file_system_app.h
index 9a5983cbcedba7a047ce3d54028a1788812a46ae..91c18bc084e9acde93e1abed56ec740de0afa06b 100644
--- a/components/filesystem/file_system_app.h
+++ b/components/filesystem/file_system_app.h
@@ -31,8 +31,8 @@ class FileSystemApp : public mojo::ShellClient,
   static base::FilePath GetUserDataDir();
 
   // |mojo::ShellClient| override:
-  void Initialize(mojo::Connector* connector, const std::string& url,
-                  const std::string& user_id, uint32_t id) override;
+  void Initialize(mojo::Connector* connector, const mojo::Identity& identity,
+                  uint32_t id) override;
   bool AcceptConnection(mojo::Connection* connection) override;
 
   // |InterfaceFactory<Files>| implementation: