Revert of Integrate registry_hash_store_contents with the rest of tracked prefs.

components/user_prefs/tracked/pref_hash_filter.h

Index: components/user_prefs/tracked/pref_hash_filter.h
diff --git a/components/user_prefs/tracked/pref_hash_filter.h b/components/user_prefs/tracked/pref_hash_filter.h
index 07c92db9506180b5c7da529ba8dd5f7201c2ff21..fae8dcd6d5659c4274efd06ef5e8737e6373835b 100644
--- a/components/user_prefs/tracked/pref_hash_filter.h
+++ b/components/user_prefs/tracked/pref_hash_filter.h
@@ -15,10 +15,7 @@
 #include "base/callback.h"
 #include "base/compiler_specific.h"
 #include "base/containers/scoped_ptr_hash_map.h"
-#include "base/files/file_path.h"
 #include "base/macros.h"
-#include "base/optional.h"
-#include "components/user_prefs/tracked/hash_store_contents.h"
 #include "components/user_prefs/tracked/interceptable_pref_filter.h"
 #include "components/user_prefs/tracked/tracked_preference.h"
 
@@ -67,9 +64,6 @@
     ValueType value_type;
   };
 
-  using StoreContentsPair = std::pair<std::unique_ptr<PrefHashStore>,
-                                      std::unique_ptr<HashStoreContents>>;
-
   // Constructs a PrefHashFilter tracking the specified |tracked_preferences|
   // using |pref_hash_store| to check/store hashes. An optional |delegate| is
   // notified of the status of each preference as it is checked.
@@ -79,11 +73,8 @@
   // than |tracked_preferences.size()|). If |report_super_mac_validity| is true,
   // the state of the super MAC will be reported via UMA during
   // FinalizeFilterOnLoad.
-  // |external_validation_hash_store_pair_| will be used (if non-null) to
-  // perform extra validations without triggering resets.
   PrefHashFilter(
       std::unique_ptr<PrefHashStore> pref_hash_store,
-      StoreContentsPair external_validation_hash_store_pair_,
       const std::vector<TrackedPreferenceMetadata>& tracked_preferences,
       const base::Closure& on_reset_on_load,
       TrackedPreferenceValidationDelegate* delegate,
@@ -120,25 +111,6 @@
       std::unique_ptr<base::DictionaryValue> pref_store_contents,
       bool prefs_altered) override;
 
-  // Helper function to generate FilterSerializeData()'s pre-write and
-  // post-write callbacks. The returned callbacks are thread-safe.
-  OnWriteCallbackPair GetOnWriteSynchronousCallbacks(
-      base::DictionaryValue* pref_store_contents);
-
-  // Clears the MACs contained in |external_validation_hash_store_contents|
-  // which are present in |paths_to_clear|.
-  static void ClearFromExternalStore(
-      HashStoreContents* external_validation_hash_store_contents,
-      const base::DictionaryValue* changed_paths_and_macs);
-
-  // Flushes the MACs contained in |changed_paths_and_mac| to
-  // external_hash_store_contents if |write_success|, otherwise discards the
-  // changes.
-  static void FlushToExternalStore(
-      std::unique_ptr<HashStoreContents> external_hash_store_contents,
-      std::unique_ptr<base::DictionaryValue> changed_paths_and_macs,
-      bool write_success);
-
   // Callback to be invoked only once (and subsequently reset) on the next
   // FilterOnLoad event. It will be allowed to modify the |prefs| handed to
   // FilterOnLoad before handing them back to this PrefHashFilter.
@@ -149,17 +121,11 @@
   typedef base::ScopedPtrHashMap<std::string,
                                  std::unique_ptr<TrackedPreference>>
       TrackedPreferencesMap;
-
   // A map from changed paths to their corresponding TrackedPreferences (which
   // aren't owned by this map).
   typedef std::map<std::string, const TrackedPreference*> ChangedPathsMap;
 
   std::unique_ptr<PrefHashStore> pref_hash_store_;
-
-  // A store and contents on which to perform extra validations without
-  // triggering resets.
-  // Will be null if the platform does not support external validation.
-  const base::Optional<StoreContentsPair> external_validation_hash_store_pair_;
 
   // Invoked if a reset occurs in a call to FilterOnLoad.
   const base::Closure on_reset_on_load_;