This CL replaces user_manager::UserID with AccountId.

components/user_manager/fake_user_manager.h

 // Copyright 2014 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 COMPONENTS_USER_MANAGER_FAKE_USER_MANAGER_H_
 #define COMPONENTS_USER_MANAGER_FAKE_USER_MANAGER_H_
 
 #include <map>
 #include <string>
 
 #include "base/memory/scoped_ptr.h"
+#include "components/signin/core/account_id/account_id.h"
 #include "components/user_manager/user.h"
 #include "components/user_manager/user_manager_base.h"
 
 namespace user_manager {
 
 // Fake user manager with a barebones implementation. Users can be added
 // and set as logged in, and those users can be returned.
 class USER_MANAGER_EXPORT FakeUserManager : public UserManagerBase {
  public:
   FakeUserManager();
   ~FakeUserManager() override;
 
   // Create and add a new user. Created user is not affiliated with the domain,
   // that owns the device.
-  virtual const user_manager::User* AddUser(const std::string& email);
+  virtual const user_manager::User* AddUser(const AccountId& account_id);
 
   // The same as AddUser() but allows to specify user affiliation with the
   // domain, that owns the device.
   virtual const user_manager::User* AddUserWithAffiliation(
-      const std::string& email, bool is_affiliated);
+      const AccountId& account_id,
+      bool is_affiliated);
 
   // Calculates the user name hash and calls UserLoggedIn to login a user.
-  void LoginUser(const std::string& email);
+  void LoginUser(const AccountId& account_id);
 
   // UserManager overrides.
   const user_manager::UserList& GetUsers() const override;
   user_manager::UserList GetUsersAllowedForMultiProfile() const override;
   const user_manager::UserList& GetLoggedInUsers() const override;
 
   // Set the user as logged in.
-  void UserLoggedIn(const std::string& email,
+  void UserLoggedIn(const AccountId& account_id,
                     const std::string& username_hash,
                     bool browser_restart) override;
 
   const user_manager::User* GetActiveUser() const override;
   user_manager::User* GetActiveUser() override;
-  void SwitchActiveUser(const std::string& email) override;
-  void SaveUserDisplayName(const std::string& username,
+  void SwitchActiveUser(const AccountId& account_id) override;
+  void SaveUserDisplayName(const AccountId& account_id,
                            const base::string16& display_name) override;
 
   // Not implemented.
-  void UpdateUserAccountData(const std::string& user_id,
+  void UpdateUserAccountData(const AccountId& account_id,
                              const UserAccountData& account_data) override {}
   void Shutdown() override {}
   const user_manager::UserList& GetLRULoggedInUsers() const override;
   user_manager::UserList GetUnlockUsers() const override;
-  const std::string& GetOwnerEmail() const override;
+  const AccountId& GetOwnerAccountId() const override;
   void SessionStarted() override {}
-  void RemoveUser(const std::string& email,
+  void RemoveUser(const AccountId& account_id,
                   user_manager::RemoveUserDelegate* delegate) override {}
-  void RemoveUserFromList(const std::string& email) override;
-  bool IsKnownUser(const std::string& email) const override;
-  const user_manager::User* FindUser(const std::string& email) const override;
-  user_manager::User* FindUserAndModify(const std::string& email) override;
+  void RemoveUserFromList(const AccountId& account_id) override;
+  bool IsKnownUser(const AccountId& account_id) const override;
+  const user_manager::User* FindUser(
+      const AccountId& account_id) const override;
+  user_manager::User* FindUserAndModify(const AccountId& account_id) override;
   const user_manager::User* GetLoggedInUser() const override;
   user_manager::User* GetLoggedInUser() override;
   const user_manager::User* GetPrimaryUser() const override;
   void SaveUserOAuthStatus(
-      const std::string& username,
+      const AccountId& account_id,
       user_manager::User::OAuthTokenStatus oauth_token_status) override {}
-  void SaveForceOnlineSignin(const std::string& user_id,
+  void SaveForceOnlineSignin(const AccountId& account_id,
                              bool force_online_signin) override {}
-  base::string16 GetUserDisplayName(const std::string& username) const override;
-  void SaveUserDisplayEmail(const std::string& username,
+  base::string16 GetUserDisplayName(const AccountId& account_id) const override;
+  void SaveUserDisplayEmail(const AccountId& account_id,
                             const std::string& display_email) override {}
-  std::string GetUserDisplayEmail(const std::string& username) const override;
+  std::string GetUserDisplayEmail(const AccountId& account_id) const override;
   bool IsCurrentUserOwner() const override;
   bool IsCurrentUserNew() const override;
   bool IsCurrentUserNonCryptohomeDataEphemeral() const override;
   bool CanCurrentUserLock() const override;
   bool IsUserLoggedIn() const override;
   bool IsLoggedInAsUserWithGaiaAccount() const override;
   bool IsLoggedInAsPublicAccount() const override;
   bool IsLoggedInAsGuest() const override;
   bool IsLoggedInAsSupervisedUser() const override;
   bool IsLoggedInAsKioskApp() const override;
   bool IsLoggedInAsStub() const override;
   bool IsSessionStarted() const override;
   bool IsUserNonCryptohomeDataEphemeral(
-      const std::string& email) const override;
+      const AccountId& account_id) const override;
   void AddObserver(Observer* obs) override {}
   void RemoveObserver(Observer* obs) override {}
   void AddSessionStateObserver(UserSessionStateObserver* obs) override {}
   void RemoveSessionStateObserver(UserSessionStateObserver* obs) override {}
   void NotifyLocalStateChanged() override {}
   bool AreSupervisedUsersAllowed() const override;
 
   // UserManagerBase overrides:
   bool AreEphemeralUsersEnabled() const override;
   const std::string& GetApplicationLocale() const override;
   PrefService* GetLocalState() const override;
   void HandleUserOAuthTokenStatusChange(
-      const std::string& user_id,
+      const AccountId& account_id,
       user_manager::User::OAuthTokenStatus status) const override {}
   bool IsEnterpriseManaged() const override;
-  void LoadPublicAccounts(std::set<std::string>* public_sessions_set) override {
-  }
+  void LoadPublicAccounts(std::set<AccountId>* public_sessions_set) override {}
   void PerformPreUserListLoadingActions() override {}
   void PerformPostUserListLoadingActions() override {}
   void PerformPostUserLoggedInActions(bool browser_restart) override {}
-  bool IsDemoApp(const std::string& user_id) const override;
-  bool IsKioskApp(const std::string& user_id) const override;
+  bool IsDemoApp(const AccountId& account_id) const override;
+  bool IsKioskApp(const AccountId& account_id) const override;
   bool IsPublicAccountMarkedForRemoval(
-      const std::string& user_id) const override;
+      const AccountId& account_id) const override;
   void DemoAccountLoggedIn() override {}
-  void KioskAppLoggedIn(const std::string& app_id) override {}
+  void KioskAppLoggedIn(const AccountId& kiosk_app_account_id) override {}
   void PublicAccountUserLoggedIn(user_manager::User* user) override {}
-  void SupervisedUserLoggedIn(const std::string& user_id) override {}
-  void OnUserRemoved(const std::string& user_id) override {}
+  void SupervisedUserLoggedIn(const AccountId& account_id) override {}
+  void OnUserRemoved(const AccountId& account_id) override {}
 
  protected:
   user_manager::User* primary_user_;
 
   // If set this is the active user. If empty, the first created user is the
   // active user.
-  std::string active_user_id_;
+  AccountId active_account_id_ = EmptyAccountId();
 
  private:
   // We use this internal function for const-correctness.
   user_manager::User* GetActiveUserInternal() const;
 
-  // stub, always empty string.
-  std::string owner_email_;
+  // stub, always empty.
+  AccountId owner_account_id_ = EmptyAccountId();
 
   DISALLOW_COPY_AND_ASSIGN(FakeUserManager);
 };
 
 }  // namespace user_manager
 
 #endif  // COMPONENTS_USER_MANAGER_FAKE_USER_MANAGER_H_