Only show Last N Pages in the UI when the corresponding tab is visible.

components/ntp_snippets/offline_pages/offline_pages_test_utils.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_OFFLINE_PAGES_OFFLINE_PAGES_TEST_UTILS_H_
 #define COMPONENTS_NTP_SNIPPETS_OFFLINE_PAGES_OFFLINE_PAGES_TEST_UTILS_H_
 
 #include "components/ntp_snippets/content_suggestion.h"
 #include "components/offline_pages/core/offline_page_item.h"
 #include "components/offline_pages/core/stub_offline_page_model.h"
@@ skipping 21 matching lines @@
 
  private:
   std::vector<offline_pages::OfflinePageItem> items_;
   bool is_loaded_;
 
   DISALLOW_COPY_AND_ASSIGN(FakeOfflinePageModel);
 };
 
 offline_pages::OfflinePageItem CreateDummyOfflinePageItem(
     int id,
+    const offline_pages::ClientId& client_id);
+
+offline_pages::OfflinePageItem CreateDummyOfflinePageItem(
+    int id,
     const std::string& name_space);
 
 void CaptureDismissedSuggestions(
     std::vector<ntp_snippets::ContentSuggestion>* captured_suggestions,
     std::vector<ntp_snippets::ContentSuggestion> dismissed_suggestions);
 
 }  // namespace test
 }  // namespace ntp_snippets
 
 #endif  // COMPONENTS_NTP_SNIPPETS_OFFLINE_PAGES_OFFLINE_PAGES_TEST_UTILS_H_