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

components/gcm_driver/gcm_driver_android.cc

 // Copyright 2014 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/gcm_driver/gcm_driver_android.h"
 
 #include <stddef.h>
 #include <stdint.h>
 
 #include "base/android/context_utils.h"
@@ skipping 91 matching lines @@
     std::vector<uint8_t> raw_data;
     JavaByteArrayToByteVector(env, j_raw_data, &raw_data);
     message.raw_data.assign(raw_data.begin(), raw_data.end());
 
     message_byte_size += message.raw_data.size();
   }
 
   recorder_.RecordDataMessageReceived(app_id, message.sender_id,
                                       message_byte_size);
 
-  DispatchMessage(app_id, message);
+  DispatchMessage(app_id, message,
+                  base::Bind(&GCMDriverAndroid::SendMessageReceipt,

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

Why isn't this BindToCurrentThread? If we're telling AppHandlers that it's OK to
invoke the callback on any thread, we need to be consistent about that.

[harkness, 2017/01/19 13:20:42]

Done.

+                             weak_ptr_factory_.GetWeakPtr(), app_id, ""));

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

Why the empty string for |message_id|? Can we just not pass it until it's
available?

[harkness, 2017/01/19 13:20:42]

Sure, that's a good idea. Done.

+}
+
+void GCMDriverAndroid::SendMessageReceipt(const std::string& app_id,
+                                          const std::string& message_id,
+                                          GCMMessageStatus status) {
+  // TODO(harkness) Implement message receipts in android.

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

nit: please mention a bug

[harkness, 2017/01/19 13:20:42]

Done.

+  NOTIMPLEMENTED();
 }
 
 // static
 bool GCMDriverAndroid::RegisterJni(JNIEnv* env) {
   return RegisterNativesImpl(env);
 }
 
 void GCMDriverAndroid::OnSignedIn() {
 }
 
@@ skipping 137 matching lines @@
   NOTIMPLEMENTED();
 }
 
 void GCMDriverAndroid::RecordDecryptionFailure(
     const std::string& app_id,
     GCMEncryptionProvider::DecryptionResult result) {
   recorder_.RecordDecryptionFailure(app_id, result);
 }
 
 }  // namespace gcm