Refactor FileBasedPolicyProvider, introduce AsynchronousPolicyProvider.

chrome/browser/policy/asynchronous_policy_provider.cc

+// Copyright (c) 2010 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.
+
+#include "chrome/browser/policy/asynchronous_policy_provider.h"
+
+#include "chrome/browser/browser_thread.h"
+#include "chrome/browser/policy/asynchronous_policy_loader.h"
+
+namespace policy {
+
+AsynchronousPolicyProvider::AsynchronousPolicyProvider(
+    const PolicyDefinitionList* policy_list,
+    scoped_refptr<AsynchronousPolicyLoader> loader)
+    : ConfigurationPolicyProvider(policy_list),
+      loader_(loader) {
+  // TODO(danno): This explicit registration of the provider shouldn't be
+  // necessary. Instead, the PrefStore should explicitly observe preference
+  // changes that are reported during the policy change.
+  loader_->SetProvider(this);
+  loader_->Init();
+}
+
+AsynchronousPolicyProvider::~AsynchronousPolicyProvider() {
+  DCHECK(CalledOnValidThread());
+  loader_->Stop();
+  loader_->SetProvider(NULL);
+}
+
+bool AsynchronousPolicyProvider::Provide(
+    ConfigurationPolicyStoreInterface* store) {
+  DCHECK(CalledOnValidThread());
+  DCHECK(loader_->policy());
+  DecodePolicyValueTree(loader_->policy(), store);
+  return true;
+}
+
+scoped_refptr<AsynchronousPolicyLoader> AsynchronousPolicyProvider::loader() {
+  return loader_;
+}
+
+}  // namespace policy