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

components/ntp_snippets/breaking_news/content_suggestions_gcm_app_handler.cc

+// 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.
+
+#include "components/ntp_snippets/breaking_news/content_suggestions_gcm_app_handler.h"
+
+#include "base/strings/string_util.h"
+#include "components/gcm_driver/gcm_driver.h"
+#include "components/gcm_driver/gcm_profile_service.h"
+#include "components/gcm_driver/instance_id/instance_id.h"
+#include "components/gcm_driver/instance_id/instance_id_driver.h"
+#include "content/public/common/push_messaging_status.h"
+
+using instance_id::InstanceID;
+
+namespace ntp_snippets {
+
+// Our sender ID we send up with all of our GCM messages.

[sfiera, 2017/06/02 08:43:05]

This doesn't tell me a lot more than the variable name. Maybe there are docs you
could link to?

[mamir, 2017/06/02 13:13:56]

Done.

+const char* kContentSuggestionsGCMAppID = "com.google.contentsuggestions.gcm";
+const char* kContentSuggestionsGCMSenderId = "128223710667";
+
+// Scope passed to getToken to obtain GCM registration tokens.

[sfiera, 2017/06/02 08:43:04]

// OAuth2 scope…

[mamir, 2017/06/02 13:13:57]

Done.

+// Must match Java GoogleCloudMessaging.INSTANCE_ID_SCOPE.
+const char kGCMScope[] = "GCM";
+
+ContentSuggestionsGCMAppHandler::ContentSuggestionsGCMAppHandler(
+    gcm::GCMDriver* gcm_driver,
+    std::unique_ptr<BreakingNewsSubscriptionManager> subscription_manager)
+    : gcm_driver_(gcm_driver),
+      subscription_manager_(std::move(subscription_manager)),
+      weak_factory_(this) {
+  if (gcm_driver_->GetAppHandler(kContentSuggestionsGCMAppID) == this) {

[sfiera, 2017/06/02 08:43:05]

I'm not sure how this is possible. We are in the constructor—if anything points
to `this` before the constructor runs, it was a dangling pointer.

[mamir, 2017/06/02 13:13:57]

Acknowledged.

+    // GCM app handler already added.
+    return;
+  }
+
+  gcm_driver_->AddAppHandler(kContentSuggestionsGCMAppID, this);
+}
+
+void ContentSuggestionsGCMAppHandler::DoSubscribe(
+    instance_id::InstanceIDDriver* instance_id_driver) {
+  instance_id_driver->GetInstanceID(kContentSuggestionsGCMAppID)
+      ->GetToken(kContentSuggestionsGCMSenderId, kGCMScope,
+                 std::map<std::string, std::string>() /* options */,
+                 base::Bind(&ContentSuggestionsGCMAppHandler::DidSubscribe,
+                            weak_factory_.GetWeakPtr()));
+}
+
+void ContentSuggestionsGCMAppHandler::Shutdown() {

[sfiera, 2017/06/02 08:43:05]

Can this object be destroyed without being Shutdown() first?
If so, then we should probably remove the app handler in the destructor too.
If not, then let's DCHECK() that the app handler was removed in the destructor.

[mamir, 2017/06/02 13:13:57]

Done.

+  gcm_driver_->RemoveAppHandler(kContentSuggestionsGCMAppID);
+}
+
+void ContentSuggestionsGCMAppHandler::ShutdownHandler() {}
+
+void ContentSuggestionsGCMAppHandler::OnStoreReset() {}
+
+void ContentSuggestionsGCMAppHandler::OnMessage(
+    const std::string& app_id,
+    const gcm::IncomingMessage& message) {
+  // TODO(mamir): Implement Show notification and update the feed.

[sfiera, 2017/06/02 08:43:04]

Add a DVLOG(1) for now?

[mamir, 2017/06/02 13:13:57]

Done.

+}
+
+void ContentSuggestionsGCMAppHandler::OnMessagesDeleted(
+    const std::string& app_id) {
+  // Messages don't get deleted.
+}
+
+void ContentSuggestionsGCMAppHandler::OnSendError(
+    const std::string& app_id,
+    const gcm::GCMClient::SendErrorDetails& details) {
+  // Should never be called because we don't send GCM messages to
+  // the server.
+}
+
+void ContentSuggestionsGCMAppHandler::OnSendAcknowledged(
+    const std::string& app_id,
+    const std::string& message_id) {
+  // Should never be called because we don't send GCM messages to
+  // the server.
+}
+
+void ContentSuggestionsGCMAppHandler::DidSubscribe(
+    const std::string& subscription_id,
+    InstanceID::Result result) {
+  content::PushRegistrationStatus status =
+      content::PUSH_REGISTRATION_STATUS_SERVICE_ERROR;
+
+  switch (result) {
+    case InstanceID::SUCCESS:
+      // TODO (mamir): store the subscription_id in prefs.
+      subscription_manager_->Subscribe(subscription_id);
+      return;
+    case InstanceID::INVALID_PARAMETER:
+    case InstanceID::DISABLED:
+    case InstanceID::ASYNC_OPERATION_PENDING:
+    case InstanceID::SERVER_ERROR:
+    case InstanceID::UNKNOWN_ERROR:
+      DLOG(WARNING)
+          << "Push messaging subscription failed; InstanceID::Result = "
+          << result;
+      status = content::PUSH_REGISTRATION_STATUS_SERVICE_ERROR;
+      break;
+    case InstanceID::NETWORK_ERROR:
+      status = content::PUSH_REGISTRATION_STATUS_NETWORK_ERROR;
+      break;
+  }
+  DLOG(WARNING) << "Status = " << status;
+}
+}  // namespace ntp_snippets