Multi-strategy based tracking.

chrome/browser/prefs/pref_hash_store_impl.h

Index: chrome/browser/prefs/pref_hash_store_impl.h
diff --git a/chrome/browser/prefs/pref_hash_store_impl.h b/chrome/browser/prefs/pref_hash_store_impl.h
index 1d3f5817e32747b374b50ccdea74fb93d0222514..f99f0fa7ac2106df72632829c3975af9a4b4a0b4 100644
--- a/chrome/browser/prefs/pref_hash_store_impl.h
+++ b/chrome/browser/prefs/pref_hash_store_impl.h
@@ -16,10 +16,6 @@
 class PrefRegistrySimple;
 class PrefService;
 
-namespace base {
-class Value;
-}  // namespace base
-
 // Implements PrefHashStoreImpl by storing preference hashes in a PrefService.
 class PrefHashStoreImpl : public PrefHashStore {
  public:
@@ -44,8 +40,21 @@ class PrefHashStoreImpl : public PrefHashStore {
                                 const base::Value* value) const OVERRIDE;
   virtual void StoreHash(const std::string& path,
                          const base::Value* value) OVERRIDE;
+  virtual ValueState CheckSplitValue(
+      const std::string& path,
+      const base::DictionaryValue* initial_split_value,
+      std::vector<std::string>* invalid_keys) const OVERRIDE;
+  virtual void StoreSplitHash(
+      const std::string& path,
+      const base::DictionaryValue* split_value) OVERRIDE;
 
  private:
+  // Clears any hashes stored for |path|.
+  void ClearPath(const std::string& path);
+
+  // Returns true if there are any hashes stored for |path|.
+  bool HasPath(const std::string& path) const;
+
   std::string hash_store_id_;
   PrefHashCalculator pref_hash_calculator_;
   PrefService* local_state_;