New snippets now replace old snippets and do not merge

components/ntp_snippets/category_factory.h

Index: components/ntp_snippets/category_factory.h
diff --git a/components/ntp_snippets/category_factory.h b/components/ntp_snippets/category_factory.h
index dcaec00d7320d7e5e4fc6e2223cdd497001dda04..5bbd9972ed4b0b32d70992531a5b089b0e6c6459 100644
--- a/components/ntp_snippets/category_factory.h
+++ b/components/ntp_snippets/category_factory.h
@@ -6,6 +6,7 @@
 #define COMPONENTS_NTP_SNIPPETS_CATEGORY_FACTORY_H_
 
 #include <map>
+#include <string>
 #include <vector>
 
 #include "base/macros.h"
@@ -43,6 +44,19 @@ class CategoryFactory {
   // |FromRemoteCategory|.
   bool CompareCategories(const Category& left, const Category& right) const;
 
+  // Creates a unique ID. The given |within_category_id| must be unique among
+  // all suggestion IDs from this provider for the given |category|. This method
+  // combines it with the |category| to form an ID that is unique
+  // application-wide, because this provider is the only one that provides
+  // suggestions for that category.
+  std::string MakeUniqueID(Category category,
+                           const std::string& within_category_id) const;
+
+  // Reverse functions for MakeUniqueID()
+  Category GetCategoryFromUniqueID(const std::string& unique_id);
+  std::string GetWithinCategoryIDFromUniqueID(
+      const std::string& unique_id) const;
+
  private:
   bool CategoryExists(int id);
   void AddKnownCategory(KnownCategories known_category);