Change userid from a uint32_t to a string guid

mash/screenlock/screenlock.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/screenlock/screenlock.h"
 
 #include "base/macros.h"
 #include "base/strings/utf_string_conversions.h"
 #include "components/mus/public/cpp/property_type_converters.h"
 #include "mash/shell/public/interfaces/shell.mojom.h"
@@ skipping 58 matching lines @@
 
   DISALLOW_COPY_AND_ASSIGN(ScreenlockView);
 };
 
 }  // namespace
 
 Screenlock::Screenlock() {}
 Screenlock::~Screenlock() {}
 
 void Screenlock::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);
 
   mash::shell::mojom::ShellPtr mash_shell;
   connector->ConnectToInterface("mojo:mash_shell", &mash_shell);
   mash_shell->AddScreenlockStateListener(
       bindings_.CreateInterfacePtrAndBind(this));
 
   aura_init_.reset(new views::AuraInit(connector, "views_mus_resources.pak"));
   views::WindowManagerConnection::Create(connector);
 
@@ skipping 14 matching lines @@
   widget->Show();
 }
 
 void Screenlock::ScreenlockStateChanged(bool screen_locked) {
   if (!screen_locked)
     base::MessageLoop::current()->QuitWhenIdle();
 }
 
 }  // namespace screenlock
 }  // namespace main