Multi-strategy based tracking.

chrome/browser/prefs/pref_hash_store.h

Index: chrome/browser/prefs/pref_hash_store.h
diff --git a/chrome/browser/prefs/pref_hash_store.h b/chrome/browser/prefs/pref_hash_store.h
index 6f1dcc54b2f9a0fb7d0c4b879d8210744a804772..d06556adb96222e8f8d7d853635a8ef52ca26d6b 100644
--- a/chrome/browser/prefs/pref_hash_store.h
+++ b/chrome/browser/prefs/pref_hash_store.h
@@ -6,10 +6,10 @@
 #define CHROME_BROWSER_PREFS_PREF_HASH_STORE_H_
 
 #include <string>
-
-#include "base/memory/scoped_ptr.h"
+#include <vector>
 
 namespace base {
+class DictionaryValue;
 class Value;
 }  // namespace base
 
@@ -61,6 +61,23 @@ class PrefHashStore {
   // Stores a hash of the current |value| of the preference at |path|.
   virtual void StoreHash(const std::string& path,
                          const base::Value* value) = 0;
+
+  // Checks |initial_value| against the existing stored hashes for the split
+  // preference at |path|. |initial_split_value| being an empty dictionary or
+  // NULL is equivalent. |invalid_keys| must initially be empty. |invalid_keys|
+  // will not be modified unless the return value is CHANGED, in which case it
+  // will be filled with the keys that are considered invalid (unknown or
+  // changed).
+  virtual ValueState CheckSplitValue(
+      const std::string& path,
+      const base::DictionaryValue* initial_split_value,
+      std::vector<std::string>* invalid_keys) const = 0;
+
+  // Stores hashes for the |value| of the split preference at |path|.
+  // |split_value| being an empty dictionary or NULL is equivalent.
+  virtual void StoreSplitHash(
+      const std::string& path,
+      const base::DictionaryValue* split_value) = 0;
 };
 
 #endif  // CHROME_BROWSER_PREFS_PREF_HASH_STORE_H_