Add IsAuthenticated() method to SigninManager.

components/signin/core/browser/signin_manager_base.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.
 //
 // The signin manager encapsulates some functionality tracking
 // which user is signed in.
 //
 // **NOTE** on semantics of SigninManager:
 //
 // Once a signin is successful, the username becomes "established" and will not
@@ skipping 82 matching lines @@
   // GetAuthenticatedUsername().  Example: to show the string "Signed in as XXX"
   // in the hotdog menu.
   const std::string& GetAuthenticatedAccountId() const;
 
   // Sets the user name.  Note: |username| should be already authenticated as
   // this is a sticky operation (in contrast to StartSignIn).
   // TODO(tim): Remove this in favor of passing username on construction by
   // (by platform / depending on StartBehavior). Bug 88109.
   void SetAuthenticatedUsername(const std::string& username);
 
+  // Returns true if there is an authenticated user.
+  bool IsAuthenticated() const;
+
   // Returns true if there's a signin in progress.
   virtual bool AuthInProgress() const;
 
   // KeyedService implementation.
   virtual void Shutdown() OVERRIDE;
 
   // Methods to register or remove observers of signin.
   void AddObserver(Observer* observer);
   void RemoveObserver(Observer* observer);
 
@@ skipping 34 matching lines @@
   // The list of SigninDiagnosticObservers.
   ObserverList<signin_internals_util::SigninDiagnosticsObserver, true>
       signin_diagnostics_observers_;
 
   base::WeakPtrFactory<SigninManagerBase> weak_pointer_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(SigninManagerBase);
 };
 
 #endif  // COMPONENTS_SIGNIN_CORE_BROWSER_SIGNIN_MANAGER_BASE_H_