New snippets now replace old snippets and do not merge

components/ntp_snippets/category_factory.cc

Index: components/ntp_snippets/category_factory.cc
diff --git a/components/ntp_snippets/category_factory.cc b/components/ntp_snippets/category_factory.cc
index b45fc4a8a8bb785403167dfe29e29d4b1ff2c1c1..0c01dfee8d59045e0ac4e598c198fe8fbbde6a88 100644
--- a/components/ntp_snippets/category_factory.cc
+++ b/components/ntp_snippets/category_factory.cc
@@ -7,9 +7,18 @@
 #include <algorithm>
 
 #include "base/logging.h"
+#include "base/strings/string_number_conversions.h"
+#include "base/strings/stringprintf.h"
 
 namespace ntp_snippets {
 
+namespace {
+
+const char kCombinedIDFormat[] = "%d|%s";
+const char kSeparator = '|';
+
+}  // namespace
+
 CategoryFactory::CategoryFactory() {
   // Add all local categories in a fixed order.
   AddKnownCategory(KnownCategories::DOWNLOADS);
@@ -57,6 +66,32 @@ bool CategoryFactory::CompareCategories(const Category& left,
                                      ordered_categories_.end(), right);
 }
 
+std::string CategoryFactory::MakeUniqueID(
+    Category category,
+    const std::string& within_category_id) const {
+  return base::StringPrintf(kCombinedIDFormat, category.id(),
+                            within_category_id.c_str());
+}
+
+Category CategoryFactory::GetCategoryFromUniqueID(
+    const std::string& unique_id) {
+  size_t colon_index = unique_id.find(kSeparator);
+  DCHECK_NE(std::string::npos, colon_index) << "Not a valid unique_id: "
+                                            << unique_id;
+  int category = -1;
+  bool ret = base::StringToInt(unique_id.substr(0, colon_index), &category);
+  DCHECK(ret) << "Non-numeric category part in unique_id: " << unique_id;
+  return FromIDValue(category);
+}
+
+std::string CategoryFactory::GetWithinCategoryIDFromUniqueID(
+    const std::string& unique_id) const {
+  size_t colon_index = unique_id.find(kSeparator);
+  DCHECK_NE(std::string::npos, colon_index) << "Not a valid unique_id: "
+                                            << unique_id;
+  return unique_id.substr(colon_index + 1);
+}
+
 ////////////////////////////////////////////////////////////////////////////////
 // Private methods