Implemented system tray UI for new account management.

ash/system/user/user_accounts_delegate.h

Index: ash/system/user/user_accounts_delegate.h
diff --git a/ash/system/user/user_accounts_delegate.h b/ash/system/user/user_accounts_delegate.h
new file mode 100644
index 0000000000000000000000000000000000000000..7521bfde6e91a2bbbd920acfd5cab9080122bde9
--- /dev/null
+++ b/ash/system/user/user_accounts_delegate.h
@@ -0,0 +1,64 @@
+// 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.
+
+#include <string>
+#include <vector>
+
+#include "ash/ash_export.h"
+#include "base/macros.h"
+#include "base/observer_list.h"
+
+namespace ash {
+namespace tray {
+
+class ASH_EXPORT UserAccountsDelegate {
+ public:
+  class Observer {
+   public:
+    Observer() {}
+    virtual ~Observer() {}
+
+    // Called when account list of user has been changed.
+    virtual void AccountListChanged() = 0;
+
+   private:
+    DISALLOW_COPY_AND_ASSIGN(Observer);
+  };
+
+  UserAccountsDelegate();
+  virtual ~UserAccountsDelegate();
+
+  void AddObserver(Observer* observer);
+  void RemoveObserver(Observer* observer);
+
+  // Returns user's primary account. It has form of canonized email.
+  virtual std::string GetPrimaryAccount() = 0;
+
+  // Returns list of user's secondary accounts. They have form of canonized
+  // emails.
+  virtual std::vector<std::string> GetSecondaryAccountsList() = 0;
+
+  // Returns display name for given |account_id|. It has form of email but could
+  // be not cananized, e.g. account "test-user@gmail.com" could have display
+  // name "Test-user+AfterPlus@gmail.com".
+  virtual std::string GetAccountDisplayName(const std::string& account_id) = 0;
+
+  // Deletes given |account_id| from the list of user's account. Passing
+  // |account_id| that is not from list is no-op.
+  virtual void DeleteAccount(const std::string& account_id) = 0;
+
+  // Launches dialog that offers user to add the new account.
+  virtual void LaunchAddAccountDialog() = 0;
+
+ protected:
+  void NotifyAccountListChanged();
+
+ private:
+  ObserverList<Observer> observers_;
+
+  DISALLOW_COPY_AND_ASSIGN(UserAccountsDelegate);
+};
+
+}  // namespace tray
+}  // namespace ash