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 797da3eea3b04338f3b43380605d7d53ced89ac7..965afdaa321c02c2a6200c8404a3966a24dcfc48 100644
--- a/chrome/browser/policy/configuration_policy_handler.h
+++ b/chrome/browser/policy/configuration_policy_handler.h
@@ -9,6 +9,8 @@
 #include <vector>
 
 #include "base/basictypes.h"
+#include "base/values.h"
+#include "policy/configuration_policy_type.h"
 
 class PrefValueMap;
 
@@ -46,6 +48,37 @@ class ConfigurationPolicyHandler {
   DISALLOW_COPY_AND_ASSIGN(ConfigurationPolicyHandler);
 };
 
+// Abstract class derived from ConfigurationPolicyHandler that should be
+// subclassed to handle a single policy (not a combination of policies).
+class TypeCheckingPolicyHandler : public ConfigurationPolicyHandler {
+ public:
+  TypeCheckingPolicyHandler(ConfigurationPolicyType policy_type,
+                            base::Value::Type value_type);
+
+  // ConfigurationPolicyHandler methods:
+  virtual bool CheckPolicySettings(const PolicyMap* policies,
+                                   PolicyErrorMap* errors) OVERRIDE;
+
+ 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:
+  // The ConfigurationPolicyType of the policy.
+  ConfigurationPolicyType policy_type_;
+
+  // The type the value of the policy should have.
+  base::Value::Type value_type_;
+
+  DISALLOW_COPY_AND_ASSIGN(TypeCheckingPolicyHandler);
+};
+
 }  // namespace policy
 
 #endif  // CHROME_BROWSER_POLICY_CONFIGURATION_POLICY_HANDLER_H_