[NTP::Push] Adding BreakingNewsSuggestionsProvider

components/ntp_snippets/breaking_news/content_suggestions_gcm_app_handler.h

 // 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"
@@ skipping 11 matching lines @@
 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:
+  // TODO(mamir): Check if a better paramater datatype makes more sense.
+  using OnNewContentCallback = base::Callback<void(const base::Value& content)>;
+
   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();
+  void StartListening(OnNewContentCallback on_new_content_callback);
 
   // 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,
@@ skipping 13 matching lines @@
   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_;
+
+  // Called after every time a new message is received in OnMessage() to notify
+  // the content provider.
+  OnNewContentCallback on_new_content_callback_;
+
   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_