Provide a mechanism for the GCM driver to send message receipts to GCM.

components/gcm_driver/gcm_client_impl.cc

Index: components/gcm_driver/gcm_client_impl.cc
diff --git a/components/gcm_driver/gcm_client_impl.cc b/components/gcm_driver/gcm_client_impl.cc
index a18b5850b5d8bb4e78dca77ee4628e696dc3f20d..e4f91c615dbc3dbbfb12410cb5c40532718586c7 100644
--- a/components/gcm_driver/gcm_client_impl.cc
+++ b/components/gcm_driver/gcm_client_impl.cc
@@ -22,10 +22,13 @@
 #include "base/strings/stringprintf.h"
 #include "base/threading/thread_task_runner_handle.h"
 #include "base/time/default_clock.h"
+#include "base/time/time.h"
 #include "base/timer/timer.h"
 #include "components/crx_file/id_util.h"
 #include "components/gcm_driver/gcm_account_mapper.h"
 #include "components/gcm_driver/gcm_backoff_policy.h"
+#include "components/gcm_driver/gcm_message_status.h"

[Peter Beverloo, 2017/01/13 01:46:12]

This file is now included trice - once in gcm_client.h, once in
gcm_client_impl.h and one in the .cc file. Once will do. (Also see the comment
in that file.)

[harkness, 2017/01/19 13:20:41]

Once I changed it to enum class, it's only included once and forward declared in
the other cases.

+#include "components/sync/base/bind_to_task_runner.h"
 #include "google_apis/gcm/base/encryptor.h"
 #include "google_apis/gcm/base/mcs_message.h"
 #include "google_apis/gcm/base/mcs_util.h"
@@ -48,6 +51,15 @@ namespace gcm {
 
 namespace {
 
+const char kGcmMessageTypeKey[] = "type";
+const char kMessageReceiptType[] = "message_receipt";
+const char kReceiptMessageIdKey[] = "message_id";
+const char kReceiptStatusKey[] = "status";
+// kReceiptGCMDestinationID is the destination ID which GCM listens to for
+// upstream receipt messages.

[Peter Beverloo, 2017/01/13 01:46:12]

Who owns it? Where does the value come from? Maybe there's an e-mail address we
can include here?

[harkness, 2017/01/19 13:20:41]

I just asked Pinar and she generated the receiver ID and gave it to me. I'm not
sure what information you want in the comment? Would adding "Generated by GCM
developers" be appropriate?

+const char kReceiptGCMDestinationID[] = "1029510549786@google.com";
+const int kReceiptTTLInSeconds = 10;
+
 // Indicates a message type of the received message.
 enum MessageType {
   UNKNOWN,           // Undetermined type.
@@ -1342,6 +1354,8 @@ void GCMClientImpl::HandleIncomingMessage(const gcm::MCSMessage& message) {
       HandleIncomingSendError(app_id, data_message_stanza, message_data);
       break;
     case UNKNOWN:
+      SendMessageReceipt(data_message_stanza.id(), app_id,
+                         GCM_UNKNOWN_MESSAGE_TYPE);
       DVLOG(1) << "Unknown message_type received. Message ignored. "
                << "App ID: " << app_id << ".";
       break;
@@ -1410,8 +1424,10 @@ void GCMClientImpl::HandleIncomingDataMessage(
   recorder_.RecordDataMessageReceived(app_id, sender,
       data_message_stanza.ByteSize(), registered,
       GCMStatsRecorder::DATA_MESSAGE);
-  if (!registered)
+  if (!registered) {
+    SendMessageReceipt(data_message_stanza.id(), app_id, GCM_INVALID_SUBTYPE);
     return;
+  }
 
   IncomingMessage incoming_message;
   incoming_message.sender_id = data_message_stanza.from();
@@ -1420,7 +1436,13 @@ void GCMClientImpl::HandleIncomingDataMessage(
   incoming_message.data = message_data;
   incoming_message.raw_data = data_message_stanza.raw_data();
 
-  delegate_->OnMessageReceived(app_id, incoming_message);
+  // Pass the message up to the GCMDriver. Also pass a callback which will send
+  // a receipt for this message if invoked with a message status.
+  delegate_->OnMessageReceived(
+      app_id, incoming_message,
+      syncer::BindToCurrentThread(base::Bind(
+          &GCMClient::SendMessageReceipt, weak_ptr_factory_.GetWeakPtr(),
+          data_message_stanza.id(), app_id)));
 }
 
 void GCMClientImpl::HandleIncomingDeletedMessages(
@@ -1471,4 +1493,22 @@ bool GCMClientImpl::HasStandaloneRegisteredApp() const {
          !ExistsGCMRegistrationInMap(registrations_, kGCMAccountMapperAppId);
 }
 
+void GCMClientImpl::SendMessageReceipt(const std::string& message_id,
+                                       const std::string& app_id,
+                                       GCMMessageStatus status) {
+  DCHECK(!app_id.empty());
+
+  // Prepare a message to send to GCM which will log the status of the received
+  // message. This is aggregated by GCM to provide better error alerting.
+  OutgoingMessage message;
+  message.time_to_live = kReceiptTTLInSeconds;
+  message.id =
+      base::Int64ToString(base::Time::NowFromSystemTime().ToInternalValue());
+  message.data[kGcmMessageTypeKey] = kMessageReceiptType;
+  message.data[kReceiptMessageIdKey] = message_id;
+  message.data[kReceiptStatusKey] = base::IntToString(status);
+
+  Send(app_id, kReceiptGCMDestinationID, message);
+}
+
 }  // namespace gcm