Move OnURLsDeleted from NTPSnippetsService to ContentSuggestionsService

components/ntp_snippets/content_suggestions_service.h

Index: components/ntp_snippets/content_suggestions_service.h
diff --git a/components/ntp_snippets/content_suggestions_service.h b/components/ntp_snippets/content_suggestions_service.h
index 22e768673b40ade51f990199cc5992517b8349b6..74067d8de2c509ca6faf35bc5a0fd8b1412f29b7 100644
--- a/components/ntp_snippets/content_suggestions_service.h
+++ b/components/ntp_snippets/content_suggestions_service.h
@@ -14,6 +14,7 @@
 #include "base/observer_list.h"
 #include "base/optional.h"
 #include "base/time/time.h"
+#include "components/history/core/browser/history_service_observer.h"
 #include "components/keyed_service/core/keyed_service.h"
 #include "components/ntp_snippets/category_factory.h"
 #include "components/ntp_snippets/category_status.h"
@@ -30,7 +31,8 @@ class NTPSnippetsService;
 // Retrieves suggestions from a number of ContentSuggestionsProviders and serves
 // them grouped into categories. There can be at most one provider per category.
 class ContentSuggestionsService : public KeyedService,
-                                  public ContentSuggestionsProvider::Observer {
+                                  public ContentSuggestionsProvider::Observer,
+                                  public history::HistoryServiceObserver {
  public:
   using ImageFetchedCallback =
       base::Callback<void(const std::string& suggestion_id, const gfx::Image&)>;
@@ -180,6 +182,13 @@ class ContentSuggestionsService : public KeyedService,
                                Category category,
                                const std::string& suggestion_id) override;
 
+  // history::HistoryServiceObserver implementation.
+  void OnURLsDeleted(history::HistoryService* history_service,
+                     bool all_history,
+                     bool expired,
+                     const history::URLRows& deleted_rows,
+                     const std::set<GURL>& favicon_urls) override;
+
   // Registers the given |provider| for the given |category|, unless it is
   // already registered. Returns true if the category was newly registered or
   // false if it was present before.