Change userid from a uint32_t to a string guid

mash/browser_driver/browser_driver_application_delegate.h

 // Copyright 2015 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.
 
 #ifndef MASH_BROWSER_DRIVER_BROWSER_DRIVER_APPLICATION_DELEGATE_H_
 #define MASH_BROWSER_DRIVER_BROWSER_DRIVER_APPLICATION_DELEGATE_H_
 
 #include <stdint.h>
 
 #include <map>
@@ skipping 10 matching lines @@
 
 class BrowserDriverApplicationDelegate : public mojo::ShellClient,
                                          public mus::mojom::AcceleratorHandler {
  public:
   BrowserDriverApplicationDelegate();
   ~BrowserDriverApplicationDelegate() override;
 
  private:
   // mojo::ShellClient:
   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;
 
   // mus::mojom::AcceleratorHandler:
   void OnAccelerator(uint32_t id, mus::mojom::EventPtr event) override;
 
   void AddAccelerators();
 
   mojo::Connector* connector_;
   mojo::Binding<mus::mojom::AcceleratorHandler> binding_;
 
   DISALLOW_COPY_AND_ASSIGN(BrowserDriverApplicationDelegate);
 };
 
 }  // namespace browser_driver
 }  // namespace mash
 
 #endif  // MASH_BROWSER_DRIVER_BROWSER_DRIVER_APPLICATION_DELEGATE_H_