[NTP Snippets] Introduce ContentSuggestion::ID

components/ntp_snippets/mock_content_suggestions_provider_observer.h

 // Copyright 2016 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef COMPONENTS_NTP_SNIPPETS_MOCK_CONTENT_SUGGESTIONS_PROVIDER_OBSERVER_H_
 #define COMPONENTS_NTP_SNIPPETS_MOCK_CONTENT_SUGGESTIONS_PROVIDER_OBSERVER_H_
 
 #include <list>
 #include <vector>
 
@@ skipping 19 matching lines @@
                         std::vector<ContentSuggestion> suggestions) override;
 
   MOCK_METHOD3(OnNewSuggestions,
                void(ContentSuggestionsProvider* provider,
                     Category category,
                     const std::list<ContentSuggestion>& suggestions));
   MOCK_METHOD3(OnCategoryStatusChanged,
                void(ContentSuggestionsProvider* provider,
                     Category category,
                     CategoryStatus new_status));
-  MOCK_METHOD3(OnSuggestionInvalidated,
+  MOCK_METHOD2(OnSuggestionInvalidated,
                void(ContentSuggestionsProvider* provider,
-                    Category category,
-                    const std::string& suggestion_id));
+                    const ContentSuggestion::ID& suggestion_id));
 };
 
 }  // namespace ntp_snippets
 
 #endif  // COMPONENTS_NTP_SNIPPETS_MOCK_CONTENT_SUGGESTIONS_PROVIDER_OBSERVER_H_