Surface error messages from ONC parsing in about: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 375b8f9d6e7ef146273e3e111dd94bd0ad64eb2d..d45c9d904b96efb56a55da65be05d0f93fc91303 100644
--- a/chrome/browser/policy/configuration_policy_handler.h
+++ b/chrome/browser/policy/configuration_policy_handler.h
@@ -60,6 +60,11 @@ class TypeCheckingPolicyHandler : public ConfigurationPolicyHandler {
  protected:
   virtual ~TypeCheckingPolicyHandler();
 
+  // Runs policy checks and returns the policy value if successful.
+  bool CheckAndGetValue(const PolicyMap& policies,
+                        PolicyErrorMap* errors,
+                        const Value** value);
+
   ConfigurationPolicyType policy_type() const;
 
  private: