[NTP::SectionOrder] Add ranker section to snippets internals.

components/ntp_snippets/category_rankers/mock_category_ranker.h

Index: components/ntp_snippets/category_rankers/mock_category_ranker.h
diff --git a/components/ntp_snippets/category_rankers/mock_category_ranker.h b/components/ntp_snippets/category_rankers/mock_category_ranker.h
index 2238aeea7e74e53f2f66c572059e1015846f0acb..6dbed913c8e4d32f175bc79785e73c2297ba72af 100644
--- a/components/ntp_snippets/category_rankers/mock_category_ranker.h
+++ b/components/ntp_snippets/category_rankers/mock_category_ranker.h
@@ -24,6 +24,7 @@ class MockCategoryRanker : public CategoryRanker {
                void(Category category_to_insert, Category anchor));
   MOCK_METHOD2(InsertCategoryAfterIfNecessary,
                void(Category category_to_insert, Category anchor));
+  MOCK_METHOD0(GetDebugData, std::vector<CategoryRanker::DebugDataItem>());
   MOCK_METHOD1(OnSuggestionOpened, void(Category category));
   MOCK_METHOD1(OnCategoryDismissed, void(Category Category));
 };