Allow signin to continue even if sync is disabled by policy.

chrome/browser/signin/signin_manager.h

 // Copyright (c) 2012 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. When a user is signed in, a ClientLogin
 // request is run on their behalf. Auth tokens are fetched from Google
 // and the results are stored in the TokenService.
 //
 // **NOTE** on semantics of SigninManager:
@@ skipping 73 matching lines @@
   void Initialize(Profile* profile);
   bool IsInitialized() const;
 
   // Returns true if the passed username is allowed by policy. Virtual for
   // mocking in tests.
   virtual bool IsAllowedUsername(const std::string& username) const;
 
   // If a user has previously established a username and SignOut has not been
   // called, this will return the username.
   // Otherwise, it will return an empty string.
-  const std::string& GetAuthenticatedUsername();
+  const std::string& GetAuthenticatedUsername() 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);
 
   // Attempt to sign in this user with ClientLogin. If successful, set a
   // preference indicating the signed in user and send out a notification,
   // then start fetching tokens for the user.
@@ skipping 59 matching lines @@
 
   // content::NotificationObserver
   virtual void Observe(int type,
                        const content::NotificationSource& source,
                        const content::NotificationDetails& details) OVERRIDE;
 
   SigninGlobalError* signin_global_error() {
     return signin_global_error_.get();
   }
 
+  const SigninGlobalError* signin_global_error() const {
+    return signin_global_error_.get();
+  }
+
   // ProfileKeyedService implementation.
   virtual void Shutdown() OVERRIDE;
 
  protected:
   // Weak pointer to parent profile (protected so FakeSigninManager can access
   // it).
   Profile* profile_;
 
   // Used to show auth errors in the wrench menu. The SigninGlobalError is
   // different than most GlobalErrors in that its lifetime is controlled by
@@ skipping 82 matching lines @@
   // to one of the StartSigninXXX methods and when the sign in is either
   // successful or not.
   SigninType type_;
 
   // Temporarily saves the oauth2 refresh and access tokens when signing in
   // with credentials.  These will be passed to TokenService so that it does
   // not need to mint new ones.
   ClientOAuthResult temp_oauth_login_tokens_;
 
   // The list of SigninDiagnosticObservers.
-  ObserverList<signin_internals_util::SigninDiagnosticsObserver>
+  ObserverList<signin_internals_util::SigninDiagnosticsObserver, true>
       signin_diagnostics_observers_;
 
   base::WeakPtrFactory<SigninManager> weak_pointer_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(SigninManager);
 };
 
 #endif  // CHROME_BROWSER_SIGNIN_SIGNIN_MANAGER_H_