Refresh policies from DM server periodically

chrome/browser/policy/device_management_policy_cache.h

 // 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.
 
 #ifndef CHROME_BROWSER_POLICY_DEVICE_MANAGEMENT_POLICY_CACHE_H_
 #define CHROME_BROWSER_POLICY_DEVICE_MANAGEMENT_POLICY_CACHE_H_
 
 #include "base/file_path.h"
 #include "base/gtest_prod_util.h"
 #include "base/lock.h"
@@ skipping 15 matching lines @@
 // SetPolicy() calls, which is then persisted and decoded into the internal
 // Value representation chrome uses.
 class DeviceManagementPolicyCache {
  public:
   explicit DeviceManagementPolicyCache(const FilePath& backing_file_path);
 
   // Loads policy information from the backing file. Non-existing or erroneous
   // cache files are ignored.
   void LoadPolicyFromFile();
 
-  // Resets the policy information.
-  void SetPolicy(const em::DevicePolicyResponse& policy);
+  // Resets the policy information. Returns true if the new policy is different
+  // from the previously stored policy.
+  bool SetPolicy(const em::DevicePolicyResponse& policy);
 
   // Gets the policy information. Ownership of the return value is transferred
   // to the caller.
   DictionaryValue* GetPolicy();
 
   // Returns the time as which the policy was last fetched.
   base::Time last_policy_refresh_time() const {
     return last_policy_refresh_time_;
   }
 
@@ skipping 28 matching lines @@
   // information loaded from the file.
   bool fresh_policy_;
 
   // The time at which the policy was last refreshed.
   base::Time last_policy_refresh_time_;
 };
 
 }  // namespace policy
 
 #endif  // CHROME_BROWSER_POLICY_DEVICE_MANAGEMENT_POLICY_CACHE_H_