[NTP::Push] Add Content Suggestions GCM App Handler

components/ntp_snippets/breaking_news/content_suggestions_gcm_app_handler.h

Index: components/ntp_snippets/breaking_news/content_suggestions_gcm_app_handler.h
diff --git a/components/ntp_snippets/breaking_news/content_suggestions_gcm_app_handler.h b/components/ntp_snippets/breaking_news/content_suggestions_gcm_app_handler.h
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+++ b/components/ntp_snippets/breaking_news/content_suggestions_gcm_app_handler.h
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+// Copyright 2017 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_BREAKING_NEWS_CONTENT_SUGGESTIONS_GCM_APP_HANDLER_H_
+#define COMPONENTS_NTP_SNIPPETS_BREAKING_NEWS_CONTENT_SUGGESTIONS_GCM_APP_HANDLER_H_
+
+#include "base/memory/weak_ptr.h"
+#include "components/gcm_driver/gcm_app_handler.h"
+#include "components/gcm_driver/instance_id/instance_id.h"
+#include "components/ntp_snippets/breaking_news/subscription_manager.h"
+#include "components/prefs/pref_registry_simple.h"
+#include "components/prefs/pref_service.h"
+
+class PrefRegistrySimple;
+
+namespace gcm {
+class GCMDriver;
+}
+
+namespace instance_id {
+class InstanceIDDriver;
+}
+
+namespace ntp_snippets {
+
+// Handler for pushed GCM content suggestions. It retrieves a subscription token
+// from the GCM server and registers/unregisters itself with the GCM service to
+// be called upon received push content suggestions.
+class ContentSuggestionsGCMAppHandler : public gcm::GCMAppHandler {
+ public:
+  ContentSuggestionsGCMAppHandler(
+      gcm::GCMDriver* gcm_driver,
+      instance_id::InstanceIDDriver* instance_id_driver,
+      PrefService* pref_service_,
+      std::unique_ptr<SubscriptionManager> subscription_manager);
+
+  // If still listening, calls StopListening()
+  ~ContentSuggestionsGCMAppHandler() override;
+
+  // Subscribe to the GCM service if necessary and start listening for pushed
+  // content suggestions. Must not be called if already listening.
+  void StartListening();
+
+  // Remove the handler, and stop listening for incoming GCM messages. Any
+  // further pushed content suggestions will be ignored. Must be called while
+  // listening.
+  void StopListening();
+
+  // GCMAppHandler overrides.
+  void ShutdownHandler() override;
+  void OnStoreReset() override;
+  void OnMessage(const std::string& app_id,
+                 const gcm::IncomingMessage& message) override;
+  void OnMessagesDeleted(const std::string& app_id) override;
+  void OnSendError(const std::string& app_id,
+                   const gcm::GCMClient::SendErrorDetails& details) override;
+  void OnSendAcknowledged(const std::string& app_id,
+                          const std::string& message_id) override;
+
+  static void RegisterProfilePrefs(PrefRegistrySimple* registry);
+
+ private:
+  // Retrieves a subscription token that allows the content suggestions server
+  // to push content via GCM messages. Calling this method multiple times is not
+  // necessary but does not harm since the same token is returned everytime.
+  void Subscribe();
+
+  // Called after the subscription is obtained from the GCM server.
+  void DidSubscribe(const std::string& subscription_id,
+                    instance_id::InstanceID::Result result);
+
+  gcm::GCMDriver* const gcm_driver_;
+  instance_id::InstanceIDDriver* const instance_id_driver_;
+  PrefService* const pref_service_;
+  const std::unique_ptr<SubscriptionManager> subscription_manager_;
+  base::WeakPtrFactory<ContentSuggestionsGCMAppHandler> weak_factory_;
+
+  DISALLOW_COPY_AND_ASSIGN(ContentSuggestionsGCMAppHandler);
+};
+}  // namespace ntp_snippets
+
+#endif  // COMPONENTS_NTP_SNIPPETS_BREAKING_NEWS_CONTENT_SUGGESTIONS_GCM_APP_HANDLER_H_