Add a SigninAllowed policy.

chrome/browser/policy/configuration_policy_handler.h

Index: chrome/browser/policy/configuration_policy_handler.h
diff --git a/chrome/browser/policy/configuration_policy_handler.h b/chrome/browser/policy/configuration_policy_handler.h
index 8d75ddfb32c98bcae425a2e0c5b2cd1e15846c48..4a22cdf1efe901b415648d245915b5b5dc9f1bcd 100644
--- a/chrome/browser/policy/configuration_policy_handler.h
+++ b/chrome/browser/policy/configuration_policy_handler.h
@@ -221,6 +221,20 @@ class SyncPolicyHandler : public TypeCheckingPolicyHandler {
   DISALLOW_COPY_AND_ASSIGN(SyncPolicyHandler);
 };
 
+// ConfigurationPolicyHandler for the SigninAllowed policy.
+class SigninPolicyHandler: public TypeCheckingPolicyHandler {

[Joao da Silva, 2013/02/07 15:36:37]

This class isn't ever instantiated, so the policy won't work.

The class is also not necessary, since the policy maps directly to a boolean
pref; adding an entry for this at kSimplePolicyMap (in
configuration_policy_handler_list.cc) is enough.

[Adrian Kuegel, 2013/02/07 16:08:59]

Thanks, I understand now that this special handling is only necessary if there
is no direct mapping to a pref, right?
And in case there is no direct mapping, I would also have to instantiate the
handler from the configuration_policy_handler_list file.
I changed it to an entry in the kSimplePolicyMap.

[Joao da Silva, 2013/02/07 16:13:05]

Sounds good. Did you forget to upload that patch?

+ 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: