Change userid from a uint32_t to a string guid

mash/login/login.cc

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "mash/login/login.h"
 
 #include "base/macros.h"
 #include "base/message_loop/message_loop.h"
 #include "base/strings/utf_string_conversions.h"
 #include "components/mus/public/cpp/property_type_converters.h"
@@ skipping 54 matching lines @@
                                ps1.height());
     login_button_2_->SetBounds(login_button_1_->bounds().right() + 10,
                                button_box.y(), ps2.width(), ps2.height());
   }
 
   // Overridden from views::ButtonListener:
   void ButtonPressed(views::Button* sender, const ui::Event& event) override {
     // Login...
     mojo::Connector::ConnectParams params("mojo:mash_shell");
     if (sender == login_button_1_) {
-      login_->login()->LoginAs(3);
+      login_->login()->LoginAs("3");
     } else if (sender == login_button_2_) {
-      login_->login()->LoginAs(4);
+      login_->login()->LoginAs("4");
     } else {
       NOTREACHED();
     }
     base::MessageLoop::current()->QuitWhenIdle();
   }
 
   Login* login_;
   views::LabelButton* login_button_1_;
   views::LabelButton* login_button_2_;
 
   DISALLOW_COPY_AND_ASSIGN(LoginView);
 };
 
 }  // namespace
 
 Login::Login() {}
 Login::~Login() {}
 
 void Login::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);
 
   aura_init_.reset(new views::AuraInit(connector, "views_mus_resources.pak"));
   views::WindowManagerConnection::Create(connector);
 
   views::Widget* widget = new views::Widget;
   views::Widget::InitParams params(
       views::Widget::InitParams::TYPE_WINDOW_FRAMELESS);
   params.delegate = new LoginView(this);
 
@@ skipping 12 matching lines @@
 bool Login::AcceptConnection(mojo::Connection* connection) {
   if (connection->GetRemoteApplicationName() == "mojo:mash_init") {
     connection->GetInterface(&login_);
     return true;
   }
   return false;
 }
 
 }  // namespace login
 }  // namespace main