Create skeleton for the Prefetching store and initial pipeline step.

components/offline_pages/core/prefetch/suggested_articles_observer_unittest.cc

Index: components/offline_pages/core/prefetch/suggested_articles_observer_unittest.cc
diff --git a/components/offline_pages/core/prefetch/suggested_articles_observer_unittest.cc b/components/offline_pages/core/prefetch/suggested_articles_observer_unittest.cc
index f813d52929853115fd4d99c72bfc079c97529d94..6ed4c1b5805e65729eef922fe7b7c5112a45a41d 100644
--- a/components/offline_pages/core/prefetch/suggested_articles_observer_unittest.cc
+++ b/components/offline_pages/core/prefetch/suggested_articles_observer_unittest.cc
@@ -32,23 +32,25 @@ class TestingPrefetchDispatcher : public PrefetchDispatcher {
  public:
   TestingPrefetchDispatcher() = default;
 
+  void SetService(PrefetchService* service) override{};
+
   void AddCandidatePrefetchURLs(
-      const std::vector<PrefetchURL>& suggested_urls) override {
-    latest_prefetch_urls = suggested_urls;
+      const std::vector<PrefetchURL>& prefetch_urls) override {
+    latest_prefetch_urls = prefetch_urls;
     new_suggestions_count++;
   }
 
   void RemoveAllUnprocessedPrefetchURLs(
       const std::string& name_space) override {
-    DCHECK_EQ(name_space, kSuggestedArticlesNamespace);
+    DCHECK_EQ(kSuggestedArticlesNamespace, name_space);
     latest_prefetch_urls.clear();
     remove_all_suggestions_count++;
   }
 
   void RemovePrefetchURLsByClientId(const ClientId& client_id) override {
-    DCHECK_EQ(client_id.name_space, kSuggestedArticlesNamespace);
+    DCHECK_EQ(kSuggestedArticlesNamespace, client_id.name_space);
     remove_by_client_id_count++;
-    last_removed_client_id = base::MakeUnique<ClientId>(client_id);
+    last_removed_client_id = client_id;
   }
 
   void BeginBackgroundTask(
@@ -56,7 +58,7 @@ class TestingPrefetchDispatcher : public PrefetchDispatcher {
   void StopBackgroundTask(ScopedBackgroundTask* task) override {}
 
   std::vector<PrefetchURL> latest_prefetch_urls;
-  std::unique_ptr<ClientId> last_removed_client_id;
+  ClientId last_removed_client_id;
 
   int new_suggestions_count = 0;
   int remove_all_suggestions_count = 0;
@@ -67,17 +69,19 @@ class TestingPrefetchService : public PrefetchService {
  public:
   TestingPrefetchService() = default;
 
-  void ObserveContentSuggestionsService(
-      ntp_snippets::ContentSuggestionsService* content_suggestions_service)
-      override {}
-  PrefetchDispatcher* GetDispatcher() override { return &dispatcher; };
   OfflineMetricsCollector* GetOfflineMetricsCollector() override {
     return nullptr;
   }
+  PrefetchDispatcher* GetPrefetchDispatcher() override { return &dispatcher; }
   PrefetchGCMHandler* GetPrefetchGCMHandler() override { return nullptr; }
+  PrefetchStore* GetPrefetchStore() override { return nullptr; }
+  void ObserveContentSuggestionsService(
+      ntp_snippets::ContentSuggestionsService* content_suggestions_service)
+      override {}
 
   TestingPrefetchDispatcher dispatcher;
 };
+
 }  // namespace
 
 class OfflinePageSuggestedArticlesObserverTest : public testing::Test {
@@ -159,8 +163,11 @@ TEST_F(OfflinePageSuggestedArticlesObserverTest, RemovesClientIdOnInvalidated) {
       ntp_snippets::ContentSuggestion::ID(category, test_url_1.spec()));
 
   EXPECT_EQ(1, test_prefetch_dispatcher()->remove_by_client_id_count);
-  EXPECT_EQ(ClientId(kSuggestedArticlesNamespace, test_url_1.spec()),
-            *test_prefetch_dispatcher()->last_removed_client_id);
+  EXPECT_EQ(test_url_1.spec(),
+            test_prefetch_dispatcher()->last_removed_client_id.id);
+  EXPECT_EQ(
+      kSuggestedArticlesNamespace,
+      test_prefetch_dispatcher()->latest_prefetch_urls[0].client_id.name_space);
 }
 
 }  // namespace offline_pages