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

components/gcm_driver/fake_gcm_client.h

Index: components/gcm_driver/fake_gcm_client.h
diff --git a/components/gcm_driver/fake_gcm_client.h b/components/gcm_driver/fake_gcm_client.h
index 251b0fd5b22fe49d83ff94857fae1f775510d225..bd1d3ec9529b15856c128a1c65ce87f722fefc69 100644
--- a/components/gcm_driver/fake_gcm_client.h
+++ b/components/gcm_driver/fake_gcm_client.h
@@ -11,6 +11,7 @@
 #include "base/macros.h"
 #include "base/memory/weak_ptr.h"
 #include "components/gcm_driver/gcm_client.h"
+#include "components/gcm_driver/gcm_message_status.h"
 #include "components/gcm_driver/gcm_stats_recorder_impl.h"
 
 namespace base {
@@ -87,6 +88,7 @@ class FakeGCMClient : public GCMClient {
   // Simulate receiving something from the server.
   // Called on UI thread.
   void ReceiveMessage(const std::string& app_id,
+                      const std::string& message_id,
                       const IncomingMessage& message);
   void DeleteMessages(const std::string& app_id);
 
@@ -94,6 +96,10 @@ class FakeGCMClient : public GCMClient {
     start_mode_overridding_ = overridding;
   }
 
+  const std::string& receipt_app_id() const { return receipt_app_id_; }
+  const std::string& receipt_message_id() const { return receipt_message_id_; }
+  GCMMessageStatus receipt_status() const { return receipt_status_; }
+
  private:
   // Called on IO thread.
   void DoStart();
@@ -105,12 +111,16 @@ class FakeGCMClient : public GCMClient {
       const linked_ptr<RegistrationInfo>& registration_info);
   void SendFinished(const std::string& app_id, const OutgoingMessage& message);
   void MessageReceived(const std::string& app_id,
-                       const IncomingMessage& message);
+                       const IncomingMessage& message,
+                       const MessageReceiptCallback& optional_receipt_callback);
   void MessagesDeleted(const std::string& app_id);
   void MessageSendError(const std::string& app_id,
                         const SendErrorDetails& send_error_details);
   void SendAcknowledgement(const std::string& app_id,
                            const std::string& message_id);
+  void SendMessageReceipt(const std::string& message_id,
+                          const std::string& app_id,
+                          GCMMessageStatus status);
 
   Delegate* delegate_;
   std::string product_category_for_subtypes_;
@@ -121,6 +131,9 @@ class FakeGCMClient : public GCMClient {
   scoped_refptr<base::SequencedTaskRunner> io_thread_;
   std::map<std::string, std::pair<std::string, std::string>> instance_id_data_;
   GCMStatsRecorderImpl recorder_;
+  std::string receipt_app_id_;
+  std::string receipt_message_id_;
+  GCMMessageStatus receipt_status_;
   base::WeakPtrFactory<FakeGCMClient> weak_ptr_factory_;
 
   DISALLOW_COPY_AND_ASSIGN(FakeGCMClient);