[Remote suggestions] Refactor the scheduler

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 b207e065b472820fe6117cb086385d66c4ad46d2..75adedba875e388a5aea9bd418ce995e57ced4b0 100644
--- a/components/ntp_snippets/content_suggestions_service.h
+++ b/components/ntp_snippets/content_suggestions_service.h
@@ -24,6 +24,7 @@
 #include "components/ntp_snippets/category_rankers/category_ranker.h"
 #include "components/ntp_snippets/category_status.h"
 #include "components/ntp_snippets/content_suggestions_provider.h"
+#include "components/ntp_snippets/remote/remote_suggestions_scheduler.h"
 #include "components/ntp_snippets/user_classifier.h"
 #include "components/signin/core/browser/signin_manager.h"
 
@@ -33,7 +34,6 @@ class PrefRegistrySimple;
 namespace ntp_snippets {
 
 class RemoteSuggestionsProvider;
-class RemoteSuggestionsScheduler;
 
 // Retrieves suggestions from a number of ContentSuggestionsProviders and serves
 // them grouped into categories. There can be at most one provider per category.
@@ -86,11 +86,16 @@ class ContentSuggestionsService : public KeyedService,
     DISABLED,
   };
 
-  ContentSuggestionsService(State state,
-                            SigninManagerBase* signin_manager,
-                            history::HistoryService* history_service,
-                            PrefService* pref_service,
-                            std::unique_ptr<CategoryRanker> category_ranker);
+  ContentSuggestionsService(
+      State state,
+      SigninManagerBase* signin_manager,         // Can be nullptr in unittests.
+      history::HistoryService* history_service,  // Can be nullptr in unittests.
+      PrefService* pref_service,
+      std::unique_ptr<CategoryRanker> category_ranker,
+      std::unique_ptr<UserClassifier> user_classifier,
+      std::unique_ptr<RemoteSuggestionsScheduler>
+          remote_suggestions_scheduler  // Can be nullptr in unittests.
+      );
   ~ContentSuggestionsService() override;
 
   // Inherited from KeyedService.
@@ -221,18 +226,17 @@ class ContentSuggestionsService : public KeyedService,
     return remote_suggestions_provider_;
   }
 
-  // The reference to RemoteSuggestionsScheduler should only be set by the
-  // factory. The interface is suited for informing about external events that
-  // have influence on scheduling remote fetches.
-  void set_remote_suggestions_scheduler(
-      ntp_snippets::RemoteSuggestionsScheduler* remote_suggestions_scheduler) {
-    remote_suggestions_scheduler_ = remote_suggestions_scheduler;
-  }
+  // The interface is suited for informing about external events that have
+  // influence on scheduling remote fetches. Can be nullptr in tests.
   RemoteSuggestionsScheduler* remote_suggestions_scheduler() {
-    return remote_suggestions_scheduler_;
+    return remote_suggestions_scheduler_.get();
   }
 
-  UserClassifier* user_classifier() { return &user_classifier_; }
+  // Can be nullptr in tests.
+  // TODO(jkrcal): The getter is only used from the bridge and from
+  // snippets-internals. Can we get rid of it with the metrics refactoring?
+  UserClassifier* user_classifier() { return user_classifier_.get(); }
+
   CategoryRanker* category_ranker() { return category_ranker_.get(); }
 
  private:
@@ -340,13 +344,14 @@ class ContentSuggestionsService : public KeyedService,
   // in |providers_|, otherwise this is a nullptr.
   RemoteSuggestionsProvider* remote_suggestions_provider_;
 
-  // Interface for informing about external events that have influence on
-  // scheduling remote fetches. Not owned.
-  RemoteSuggestionsScheduler* remote_suggestions_scheduler_;
-
   PrefService* pref_service_;
 
-  UserClassifier user_classifier_;
+  // Interface for informing about external events that have influence on
+  // scheduling remote fetches.
+  std::unique_ptr<RemoteSuggestionsScheduler> remote_suggestions_scheduler_;
+
+  // Classifies the user on the basis of long-term user interactions.
+  std::unique_ptr<UserClassifier> user_classifier_;
 
   // Provides order for categories.
   std::unique_ptr<CategoryRanker> category_ranker_;