Add a SigninAllowed policy.

chrome/browser/policy/configuration_policy_handler.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.
 
 #ifndef CHROME_BROWSER_POLICY_CONFIGURATION_POLICY_HANDLER_H_
 #define CHROME_BROWSER_POLICY_CONFIGURATION_POLICY_HANDLER_H_
 
 #include <vector>
 
 #include "base/basictypes.h"
@@ skipping 203 matching lines @@
   virtual ~SyncPolicyHandler();
 
   // ConfigurationPolicyHandler methods:
   virtual void ApplyPolicySettings(const PolicyMap& policies,
                                    PrefValueMap* prefs) OVERRIDE;
 
  private:
   DISALLOW_COPY_AND_ASSIGN(SyncPolicyHandler);
 };
 
+// ConfigurationPolicyHandler for the SigninAllowed policy.
+class SigninPolicyHandler: public TypeCheckingPolicyHandler {
+ public:
+  SigninPolicyHandler();
+  virtual ~SigninPolicyHandler();
+
+  // ConfigurationPolicyHandler methods:
+  virtual void ApplyPolicySettings(const PolicyMap& policies,
+                                   PrefValueMap* prefs) OVERRIDE;
+
+ private:
+  DISALLOW_COPY_AND_ASSIGN(SigninPolicyHandler);
+};
+
 // ConfigurationPolicyHandler for the AutofillEnabled policy.
 class AutofillPolicyHandler : public TypeCheckingPolicyHandler {
  public:
   AutofillPolicyHandler();
   virtual ~AutofillPolicyHandler();
 
   // ConfigurationPolicyHandler methods:
   virtual void ApplyPolicySettings(const PolicyMap& policies,
                                    PrefValueMap* prefs) OVERRIDE;
 
@@ skipping 224 matching lines @@
  private:
   void ApplyPolicySettingsFromHomePage(const PolicyMap& policies,
                                        PrefValueMap* prefs);
 
   DISALLOW_COPY_AND_ASSIGN(RestoreOnStartupPolicyHandler);
 };
 
 }  // namespace policy
 
 #endif  // CHROME_BROWSER_POLICY_CONFIGURATION_POLICY_HANDLER_H_