[Remote suggestions] Move all decisions to fetch to the scheduler

components/ntp_snippets/remote/remote_suggestions_provider_impl.h

Index: components/ntp_snippets/remote/remote_suggestions_provider_impl.h
diff --git a/components/ntp_snippets/remote/remote_suggestions_provider_impl.h b/components/ntp_snippets/remote/remote_suggestions_provider_impl.h
index 5fc9f77a9ebd8ccfe401e24fdeb321d0a2522c32..ecd1566b2b3d0478296cd25c2468c382a55e368a 100644
--- a/components/ntp_snippets/remote/remote_suggestions_provider_impl.h
+++ b/components/ntp_snippets/remote/remote_suggestions_provider_impl.h
@@ -47,6 +47,7 @@ namespace ntp_snippets {
 
 class CategoryRanker;
 class RemoteSuggestionsDatabase;
+class RemoteSuggestionsScheduler;
 
 // CachedImageFetcher takes care of fetching images from the network and caching
 // them in the database.
@@ -136,9 +137,13 @@ class RemoteSuggestionsProviderImpl final : public RemoteSuggestionsProvider {
   // false, some calls may trigger DCHECKs.
   bool initialized() const { return ready() || state_ == State::DISABLED; }
 
+  // Set the scheduler to be notified whenever the provider becomes active /
+  // in-active and whenever history is deleted. The initial change is also
+  // notified (switching from an initial undecided status). If the scheduler is
+  // set after the first change, it is called back immediately.
+  void SetRemoteSuggestionsScheduler(RemoteSuggestionsScheduler* scheduler);
+
   // RemoteSuggestionsProvider implementation.
-  void SetProviderStatusCallback(
-      std::unique_ptr<ProviderStatusCallback> callback) override;
   void RefetchInTheBackground(
       std::unique_ptr<FetchStatusCallback> callback) override;
 
@@ -196,21 +201,19 @@ class RemoteSuggestionsProviderImpl final : public RemoteSuggestionsProvider {
  private:
   friend class RemoteSuggestionsProviderImplTest;
 
+  // TODO(jkrcal): Mock the database to trigger the error naturally (or remove
+  // the error state and get rid of the test).
   FRIEND_TEST_ALL_PREFIXES(RemoteSuggestionsProviderImplTest,
-                           CallsProviderStatusCallbackWhenReady);
-  FRIEND_TEST_ALL_PREFIXES(RemoteSuggestionsProviderImplTest,
-                           CallsProviderStatusCallbackOnError);
-  FRIEND_TEST_ALL_PREFIXES(RemoteSuggestionsProviderImplTest,
-                           CallsProviderStatusCallbackWhenDisabled);
+                           CallsSchedulerOnError);
+  // TODO(jkrcal): Mock the status service and remove these friend declarations.
   FRIEND_TEST_ALL_PREFIXES(RemoteSuggestionsProviderImplTest,
-                           ShouldNotCrashWhenCallingEmptyCallback);
+                           CallsSchedulerWhenDisabled);
   FRIEND_TEST_ALL_PREFIXES(RemoteSuggestionsProviderImplTest,
                            DontNotifyIfNotAvailable);
   FRIEND_TEST_ALL_PREFIXES(RemoteSuggestionsProviderImplTest,
-                           RemoveExpiredDismissedContent);
-  FRIEND_TEST_ALL_PREFIXES(RemoteSuggestionsProviderImplTest, StatusChanges);
+                           CallsSchedulerWhenSignedIn);
   FRIEND_TEST_ALL_PREFIXES(RemoteSuggestionsProviderImplTest,
-                           SuggestionsFetchedOnSignInAndSignOut);
+                           CallsSchedulerWhenSignedOut);
 
   // Possible state transitions:
   //       NOT_INITED --------+
@@ -220,6 +223,8 @@ class RemoteSuggestionsProviderImpl final : public RemoteSuggestionsProvider {
   //       \       /          |
   //        v     v           |
   //     ERROR_OCCURRED <-----+
+  // TODO(jkrcal): Do we need to keep the distinction between states DISABLED
+  // and ERROR_OCCURED?
   enum class State {
     // The service has just been created. Can change to states:
     // - DISABLED: After the database is done loading,
@@ -352,6 +357,13 @@ class RemoteSuggestionsProviderImpl final : public RemoteSuggestionsProvider {
   // the file system.
   void ClearOrphanedImages();
 
+  // Clears suggestions because any history item has been removed.
+  void ClearHistoryDependentState();
+
+  // Clears suggestions for any non-history related reason (e.g., sign-in status
+  // change, etc.).
+  void ClearSuggestions();
+
   // Clears all stored suggestions and updates the observer.
   void NukeAllSuggestions();
 
@@ -442,12 +454,12 @@ class RemoteSuggestionsProviderImpl final : public RemoteSuggestionsProvider {
   bool fetch_when_ready_interactive_;
   std::unique_ptr<FetchStatusCallback> fetch_when_ready_callback_;
 
-  std::unique_ptr<ProviderStatusCallback> provider_status_callback_;
+  RemoteSuggestionsScheduler* remote_suggestions_scheduler_;
 
-  // Set to true if NukeAllSuggestions is called while the service isn't ready.
-  // The nuke will be executed once the service finishes initialization or
-  // enters the READY state.
-  bool nuke_when_initialized_;
+  // Set to true if ClearHistoryDependentState is called while the service isn't
+  // ready. The nuke will be executed once the service finishes initialization
+  // or enters the READY state.
+  bool clear_history_dependent_state_when_initialized_;
 
   // A clock for getting the time. This allows to inject a clock in tests.
   std::unique_ptr<base::Clock> clock_;