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

components/gcm_driver/fake_gcm_client.cc

Index: components/gcm_driver/fake_gcm_client.cc
diff --git a/components/gcm_driver/fake_gcm_client.cc b/components/gcm_driver/fake_gcm_client.cc
index eaa66c894d182fea831ea919e8b275cdc9edd992..abcc765dd4fa38acb4de962a020f65c941987061 100644
--- a/components/gcm_driver/fake_gcm_client.cc
+++ b/components/gcm_driver/fake_gcm_client.cc
@@ -238,15 +238,26 @@ void FakeGCMClient::PerformDelayedStart() {
 }
 
 void FakeGCMClient::ReceiveMessage(const std::string& app_id,
+                                   const std::string& message_id,
                                    const IncomingMessage& message) {
   DCHECK(ui_thread_->RunsTasksOnCurrentThread());
 
   io_thread_->PostTask(
-      FROM_HERE,
-      base::Bind(&FakeGCMClient::MessageReceived,
-                 weak_ptr_factory_.GetWeakPtr(),
-                 app_id,
-                 message));
+      FROM_HERE, base::Bind(&FakeGCMClient::MessageReceived,
+                            weak_ptr_factory_.GetWeakPtr(), app_id, message,
+                            base::Bind(&FakeGCMClient::SendMessageReceipt,

[Peter Beverloo, 2017/02/08 17:09:08]

nit: generally we have a mild preference of writing nested base::Bind()
callbacks to a local, because it significantly reduces nesting.

[harkness, 2017/02/09 16:27:29]

Done.

+                                       weak_ptr_factory_.GetWeakPtr(),
+                                       message_id, app_id)));
+}
+
+void FakeGCMClient::SendMessageReceipt(const std::string& message_id,
+                                       const std::string& app_id,
+                                       GCMMessageStatus status) {
+  DCHECK(io_thread_->RunsTasksOnCurrentThread());
+
+  receipt_message_id_ = message_id;
+  receipt_app_id_ = app_id;
+  receipt_status_ = status;
 }
 
 void FakeGCMClient::DeleteMessages(const std::string& app_id) {
@@ -303,9 +314,10 @@ void FakeGCMClient::SendFinished(const std::string& app_id,
 }
 
 void FakeGCMClient::MessageReceived(const std::string& app_id,
-                                    const IncomingMessage& message) {
+                                    const IncomingMessage& message,
+                                    const MessageReceiptCallback& callback) {
   if (delegate_)
-    delegate_->OnMessageReceived(app_id, message);
+    delegate_->OnMessageReceived(app_id, message, callback);
 }
 
 void FakeGCMClient::MessagesDeleted(const std::string& app_id) {