[NTP::Push] Adding BreakingNewsSuggestionsProvider

components/ntp_snippets/breaking_news/content_suggestions_gcm_app_handler.cc

Index: components/ntp_snippets/breaking_news/content_suggestions_gcm_app_handler.cc
diff --git a/components/ntp_snippets/breaking_news/content_suggestions_gcm_app_handler.cc b/components/ntp_snippets/breaking_news/content_suggestions_gcm_app_handler.cc
index 9e40a220bbae41106f3304591970ba1c278e4733..73531a051e3527025bb156e15cd762282b3fcd0c 100644
--- a/components/ntp_snippets/breaking_news/content_suggestions_gcm_app_handler.cc
+++ b/components/ntp_snippets/breaking_news/content_suggestions_gcm_app_handler.cc
@@ -47,12 +47,14 @@ ContentSuggestionsGCMAppHandler::~ContentSuggestionsGCMAppHandler() {
   }
 }
 
-void ContentSuggestionsGCMAppHandler::StartListening() {
+void ContentSuggestionsGCMAppHandler::StartListening(
+    OnNewContentCallback on_new_content_callback) {
 #if !defined(OS_ANDROID)
   NOTREACHED()
       << "The ContentSuggestionsGCMAppHandler should only be used on Android.";
 #endif
   Subscribe();
+  on_new_content_callback_ = std::move(on_new_content_callback);
   gcm_driver_->AddAppHandler(kContentSuggestionsGCMAppID, this);
 }
 
@@ -112,7 +114,8 @@ void ContentSuggestionsGCMAppHandler::OnStoreReset() {
 void ContentSuggestionsGCMAppHandler::OnMessage(
     const std::string& app_id,
     const gcm::IncomingMessage& message) {
-  // TODO(mamir): Implement Show notification and update the feed.
+  // TODO(mamir): Build the message.
+  on_new_content_callback_.Run(std::string());
 }
 
 void ContentSuggestionsGCMAppHandler::OnMessagesDeleted(