Make sure GetAuthenticatedAccountId() returns a canonicalized id.

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 60 matching lines @@
   // TODO(tim): kSigninAllowed is defined for all platforms in pref_names.h.
   // If kSigninAllowed pref was non-Chrome OS-only, this method wouldn't be
   // needed, but as is we provide this method to let all interested code
   // code query the value in one way, versus half using PrefService directly
   // and the other half using SigninManager.
   virtual bool IsSigninAllowed() const;
 
   // If a user has previously signed in (and has not signed out), this returns
   // the normalized email address of the account. Otherwise, it returns an empty
   // string.
-  const std::string& GetAuthenticatedUsername() const;
+  std::string GetAuthenticatedUsername() const;
 
   // If a user has previously signed in (and has not signed out), this returns
   // the account id. Otherwise, it returns an empty string.  This id can be used
   // to uniquely identify an account, so for example can be used as a key to
   // map accounts to data.
   //
   // TODO(rogerta): eventually the account id should be an obfuscated gaia id.
   // For now though, this function returns the same value as
   // GetAuthenticatedUsername() since lots of code assumes the unique id for an
   // account is the username.  For code that needs a unique id to represent the
   // connected account, call this method. Example: the AccountInfoMap type
   // in MutableProfileOAuth2TokenService.  For code that needs to know the
   // normalized email address of the connected account, use
   // GetAuthenticatedUsername().  Example: to show the string "Signed in as XXX"
   // in the hotdog menu.
-  const std::string& GetAuthenticatedAccountId() 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;
 
@@ skipping 44 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_