Create a list of policy changes before notifying observers

chrome/browser/policy/policy_service_impl.h

 // Copyright (c) 2012 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_POLICY_SERVICE_IMPL_H_
 #define CHROME_BROWSER_POLICY_POLICY_SERVICE_IMPL_H_
 
 #include <map>
 #include <set>
 #include <string>
 #include <vector>
 
 #include "base/basictypes.h"
+#include "base/memory/weak_ptr.h"
 #include "base/observer_list.h"
 #include "chrome/browser/policy/configuration_policy_provider.h"
 #include "chrome/browser/policy/policy_bundle.h"
 #include "chrome/browser/policy/policy_service.h"
 
 namespace policy {
 
 class PolicyMap;
 
 class PolicyServiceImpl : public PolicyService,
@@ skipping 16 matching lines @@
   virtual const PolicyMap& GetPolicies(
       PolicyDomain domain,
       const std::string& component_id) const OVERRIDE;
   virtual bool IsInitializationComplete() const OVERRIDE;
   virtual void RefreshPolicies(const base::Closure& callback) OVERRIDE;
 
  private:
   typedef ObserverList<PolicyService::Observer, true> Observers;
   typedef std::map<PolicyDomain, Observers*> ObserverMap;
 
+  // Information about policy changes sent to observers.
+  class PolicyChangeInfo {
+   public:
+    PolicyChangeInfo(const PolicyBundle::PolicyNamespace& policy_namespace,
+                     const PolicyMap& previous, const PolicyMap& current);
+    ~PolicyChangeInfo();
+
+    PolicyBundle::PolicyNamespace policy_namespace_;
+    PolicyMap previous_;
+    PolicyMap current_;
+  };
+
   // ConfigurationPolicyProvider::Observer overrides:
   virtual void OnUpdatePolicy(ConfigurationPolicyProvider* provider) OVERRIDE;
 
-  // Notifies observers of |ns| that its policies have changed, passing along
-  // the |previous| and the |current| policies.
+  // Posts a task to notify observers of |ns| that its policies have changed,
+  // passing along the |previous| and the |current| policies.
   void NotifyNamespaceUpdated(const PolicyBundle::PolicyNamespace& ns,
                               const PolicyMap& previous,
                               const PolicyMap& current);
 
+  // Helper function invoked by NotifyNamespaceUpdated() to notify observers
+  // via a queued task, to deal with reentrancy issues caused by observers
+  // generating policy changes.
+  void NotifyNamespaceUpdatedTask(scoped_ptr<PolicyChangeInfo> info);
+
   // Combines the policies from all the providers, and notifies the observers
   // of namespaces whose policies have been modified.
   void MergeAndTriggerUpdates();
 
   // Checks if all providers are initialized, and notifies the observers
   // if the service just became initialized.
   void CheckInitializationComplete();
 
   // Invokes all the refresh callbacks if there are no more refreshes pending.
   void CheckRefreshComplete();
@@ skipping 11 matching lines @@
   bool initialization_complete_;
 
   // Set of providers that have a pending update that was triggered by a
   // call to RefreshPolicies().
   std::set<ConfigurationPolicyProvider*> refresh_pending_;
 
   // List of callbacks to invoke once all providers refresh after a
   // RefreshPolicies() call.
   std::vector<base::Closure> refresh_callbacks_;
 
+  // Used to create tasks to delay new policy updates while we may be already
+  // processing previous policy updates.
+  base::WeakPtrFactory<PolicyServiceImpl> weak_ptr_factory_;
+
   DISALLOW_COPY_AND_ASSIGN(PolicyServiceImpl);
 };
 
 }  // namespace policy
 
 #endif  // CHROME_BROWSER_POLICY_POLICY_SERVICE_IMPL_H_