📰 The Status card reports disabled sync states

components/ntp_snippets/ntp_snippets_status_service.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_NTP_SNIPPETS_STATUS_SERVICE_H_
+#define COMPONENTS_NTP_SNIPPETS_NTP_SNIPPETS_STATUS_SERVICE_H_
+
+#include "base/callback.h"
+#include "base/gtest_prod_util.h"
+#include "base/scoped_observer.h"
+#include "components/sync_driver/sync_service_observer.h"
+
+class SigninManagerBase;
+
+namespace sync_driver {
+class SyncService;
+}
+
+namespace ntp_snippets {
+
+// On Android builds, a Java counterpart will be generated for this enum.
+// GENERATED_JAVA_ENUM_PACKAGE: org.chromium.chrome.browser.ntp.snippets
+enum class DisabledReason : int {
+  // Snippets are enabled
+  NONE,
+  // Snippets have been disabled as part of the service configuration.
+  EXPLICITLY_DISABLED,
+  // The user is not signed in, and the service requires it to be enabled.
+  SIGNED_OUT,
+  // Sync is not enabled, and the service requires it to be enabled.
+  SYNC_DISABLED,
+  // The service requires passphrase encryption to be disabled.
+  PASSPHRASE_ENCRYPTION_ENABLED,
+  // History sync is not enabled, and the service requires it to be enabled.
+  HISTORY_SYNC_DISABLED,
+  // The sync service is not completely initialized, and the status is unknown.
+  HISTORY_SYNC_STATE_UNKNOWN
+};
+
+// Aggregates data from sync and signin to notify the snippet service of
+// relevant changes in their states.
+class NTPSnippetsStatusService : public sync_driver::SyncServiceObserver {
+ public:
+  typedef base::Callback<void(DisabledReason)> DisabledReasonChangeCallback;
+
+  NTPSnippetsStatusService(SigninManagerBase* signin_manager,
+                           sync_driver::SyncService* sync_service);
+
+  ~NTPSnippetsStatusService() override;
+
+  // Starts listening for changes from the dependencies. |callback| will be
+  // called when a significant change in state is detected.
+  void Init(const DisabledReasonChangeCallback& callback);
+
+  DisabledReason disabled_reason() const { return disabled_reason_; }
+
+ private:
+  FRIEND_TEST_ALL_PREFIXES(NTPSnippetsStatusServiceTest,
+                           SyncStateCompatibility);
+
+  // sync_driver::SyncServiceObserver implementation
+  void OnStateChanged() override;
+
+  DisabledReason GetDisabledReasonFromDeps() const;
+
+  DisabledReason disabled_reason_;
+  DisabledReasonChangeCallback disabled_reason_change_callback_;
+
+  SigninManagerBase* signin_manager_;
+  sync_driver::SyncService* sync_service_;
+
+  // The observer for the SyncService. When the sync state changes,
+  // SyncService will call |OnStateChanged|.
+  ScopedObserver<sync_driver::SyncService, sync_driver::SyncServiceObserver>
+      sync_service_observer_;
+
+  DISALLOW_COPY_AND_ASSIGN(NTPSnippetsStatusService);
+};
+
+}  // namespace ntp_snippets
+
+#endif  // COMPONENTS_NTP_SNIPPETS_NTP_SNIPPETS_STATUS_SERVICE_H_