Add per-section clearing and dismissed suggestions to snippets-internals

components/ntp_snippets/content_suggestions_provider.h

Index: components/ntp_snippets/content_suggestions_provider.h
diff --git a/components/ntp_snippets/content_suggestions_provider.h b/components/ntp_snippets/content_suggestions_provider.h
index 066ea1e1f23d9ae4c9756a598c91f750e38abb49..ed99a396906f1d9a77b59eeaa01db226c8808ced 100644
--- a/components/ntp_snippets/content_suggestions_provider.h
+++ b/components/ntp_snippets/content_suggestions_provider.h
@@ -90,15 +90,23 @@ class ContentSuggestionsProvider {
   virtual void FetchSuggestionImage(const std::string& suggestion_id,
                                     const ImageFetchedCallback& callback) = 0;
 
-  // Used only for debugging purposes. Clears all caches so that the next
-  // fetch starts from scratch.
-  virtual void ClearCachedSuggestionsForDebugging() = 0;
+  // Used only for debugging purposes. Clears all caches for the given category,
+  // so that the next fetch starts from scratch.
+  virtual void ClearCachedSuggestionsForDebugging(Category category) = 0;
+
+  // Used only for debugging purposes. Retrieves suggestions for the given
+  // |category| that have previously been dismissed and are still stored in the
+  // provider. If the provider doesn't store dismissed suggestions for the given
+  // |category|, it always returns an empty vector.
+  virtual std::vector<ContentSuggestion> GetDismissedSuggestionsForDebugging(
+      Category category) = 0;
 
   // Used only for debugging purposes. Clears the cache of dismissed
-  // suggestions, if present, so that no suggestions are suppressed. This does
-  // not necessarily make previously dismissed suggestions reappear, as they may
-  // have been permanently deleted, depending on the provider implementation.
-  virtual void ClearDismissedSuggestionsForDebugging() = 0;
+  // suggestions for the given |category|, if present, so that no suggestions
+  // are suppressed. This does not necessarily make previously dismissed
+  // suggestions reappear, as they may have been permanently deleted, depending
+  // on the provider implementation.
+  virtual void ClearDismissedSuggestionsForDebugging(Category category) = 0;
 
  protected:
   ContentSuggestionsProvider(Observer* observer,