Introduced a ForwardingPolicyProvider.

chrome/browser/policy/forwarding_policy_provider.h

Index: chrome/browser/policy/forwarding_policy_provider.h
diff --git a/chrome/browser/policy/forwarding_policy_provider.h b/chrome/browser/policy/forwarding_policy_provider.h
new file mode 100644
index 0000000000000000000000000000000000000000..c5fc836647fa9939e7afc6f3202a4318e9a39dd2
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+++ b/chrome/browser/policy/forwarding_policy_provider.h
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+// Copyright (c) 2013 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_FORWARDING_POLICY_PROVIDER_H_
+#define CHROME_BROWSER_POLICY_FORWARDING_POLICY_PROVIDER_H_
+
+#include "base/basictypes.h"
+#include "base/compiler_specific.h"
+#include "chrome/browser/policy/configuration_policy_provider.h"
+#include "components/policy/core/common/policy_namespace.h"
+
+namespace policy {
+
+// A policy provider that forwards calls to another provider.
+// This provider also tracks the SchemaRegistry, and becomes ready after making
+// sure the delegate provider has refreshed its policies with an updated view
+// of the complete schema. It is expected that the delegate's SchemaRegistry
+// is a CombinedSchemaRegistry tracking the forwarding provider's registry.
+class ForwardingPolicyProvider : public ConfigurationPolicyProvider,
+                                 public ConfigurationPolicyProvider::Observer {
+ public:
+  // The |delegate| must outlive this provider.
+  explicit ForwardingPolicyProvider(ConfigurationPolicyProvider* delegate);
+  virtual ~ForwardingPolicyProvider();
+
+  // ConfigurationPolicyProvider:
+  //
+  // Note that Init() and Shutdown() are not forwarded to the |delegate_|, since
+  // this provider does not own it and its up to the |delegate_|'s owner to
+  // initialize it and shut it down.
+  //
+  // Note also that this provider may have a SchemaRegistry passed in Init()
+  // that doesn't match the |delegate_|'s; therefore OnSchemaRegistryUpdated()
+  // and OnSchemaRegistryReady() are not forwarded either. It is assumed that
+  // the |delegate_|'s SchemaRegistry contains a superset of this provider's
+  // SchemaRegistry though (i.e. it's a CombinedSchemaRegistry that contains
+  // this provider's SchemaRegistry).
+  //
+  // This provider manages its own initialization state for all policy domains
+  // except POLICY_DOMAIN_CHROME, whose status is always queried from the
+  // |delegate_|. RefreshPolicies() calls are also forwarded, since this
+  // provider doesn't have a "real" policy source of its own.
+  virtual void Init(SchemaRegistry* registry) OVERRIDE;
+  virtual bool IsInitializationComplete(PolicyDomain domain) const OVERRIDE;
+  virtual void RefreshPolicies() OVERRIDE;
+  virtual void OnSchemaRegistryReady() OVERRIDE;
+  virtual void OnSchemaRegistryUpdated(bool has_new_schemas) OVERRIDE;
+
+  // ConfigurationPolicyProvider::Observer:
+  virtual void OnUpdatePolicy(ConfigurationPolicyProvider* provider) OVERRIDE;
+
+ private:
+  enum InitializationState {
+    WAITING_FOR_REGISTRY_READY,
+    WAITING_FOR_REFRESH,
+    READY,
+  };
+
+  ConfigurationPolicyProvider* delegate_;
+  InitializationState state_;
+
+  DISALLOW_COPY_AND_ASSIGN(ForwardingPolicyProvider);
+};
+
+}  // namespace policy
+
+#endif  // CHROME_BROWSER_POLICY_FORWARDING_POLICY_PROVIDER_H_