Extend VariationParamsManager to support feature associations.

components/ntp_snippets/remote/ntp_snippets_status_service.h

Index: components/ntp_snippets/remote/ntp_snippets_status_service.h
diff --git a/components/ntp_snippets/remote/ntp_snippets_status_service.h b/components/ntp_snippets/remote/ntp_snippets_status_service.h
new file mode 100644
index 0000000000000000000000000000000000000000..27380f495475384e4319d580f4f78c13bd1f8ca1
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+++ b/components/ntp_snippets/remote/ntp_snippets_status_service.h
@@ -0,0 +1,82 @@
+// 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_REMOTE_NTP_SNIPPETS_STATUS_SERVICE_H_
+#define COMPONENTS_NTP_SNIPPETS_REMOTE_NTP_SNIPPETS_STATUS_SERVICE_H_
+
+#include "base/callback.h"
+#include "base/gtest_prod_util.h"
+#include "base/scoped_observer.h"
+#include "components/prefs/pref_change_registrar.h"
+
+class PrefRegistrySimple;
+class PrefService;
+class SigninManagerBase;
+
+namespace ntp_snippets {
+
+enum class SnippetsStatus : int {
+  // Snippets are enabled and the user is signed in.
+  ENABLED_AND_SIGNED_IN,
+  // Snippets are enabled and the user is signed out (sign in is not required).
+  ENABLED_AND_SIGNED_OUT,
+  // 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_AND_DISABLED,
+};
+
+// Aggregates data from preferences and signin to notify the snippet service of
+// relevant changes in their states.
+class NTPSnippetsStatusService {
+ public:
+  using SnippetsStatusChangeCallback =
+      base::Callback<void(SnippetsStatus /*old_status*/,
+                          SnippetsStatus /*new_status*/)>;
+
+  NTPSnippetsStatusService(SigninManagerBase* signin_manager,
+                           PrefService* pref_service);
+
+  virtual ~NTPSnippetsStatusService();
+
+  static void RegisterProfilePrefs(PrefRegistrySimple* registry);
+
+  // Starts listening for changes from the dependencies. |callback| will be
+  // called when a significant change in state is detected.
+  void Init(const SnippetsStatusChangeCallback& callback);
+
+  // To be called when the signin state changed. Will compute the new
+  // state considering the initialisation configuration and the preferences,
+  // and notify via the registered callback if appropriate.
+  void OnSignInStateChanged();
+
+ private:
+  FRIEND_TEST_ALL_PREFIXES(NTPSnippetsStatusServiceTest,
+                           SigninStateCompatibility);
+  FRIEND_TEST_ALL_PREFIXES(NTPSnippetsStatusServiceTest, DisabledViaPref);
+
+  // Callback for the PrefChangeRegistrar.
+  void OnSnippetsEnabledChanged();
+
+  void OnStateChanged(SnippetsStatus new_snippets_status);
+
+  bool IsSignedIn() const;
+
+  SnippetsStatus GetSnippetsStatusFromDeps() const;
+
+  SnippetsStatus snippets_status_;
+  SnippetsStatusChangeCallback snippets_status_change_callback_;
+
+  bool require_signin_;
+  SigninManagerBase* signin_manager_;
+  PrefService* pref_service_;
+
+  PrefChangeRegistrar pref_change_registrar_;
+
+  DISALLOW_COPY_AND_ASSIGN(NTPSnippetsStatusService);
+};
+
+}  // namespace ntp_snippets
+
+#endif  // COMPONENTS_NTP_SNIPPETS_REMOTE_NTP_SNIPPETS_STATUS_SERVICE_H_