Client-to-server messages in GCMNetworkChannel

sync/notifier/gcm_network_channel_delegate.h

+// 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.
+
+#ifndef SYNC_NOTIFIER_GCM_NETWORK_CHANNEL_DELEGATE_H_
+#define SYNC_NOTIFIER_GCM_NETWORK_CHANNEL_DELEGATE_H_
+
+#include <string>
+
+#include "base/callback.h"
+#include "google_apis/gcm/gcm_client.h"
+
+class GoogleServiceAuthError;
+
+namespace syncer {
+
+// Delegate for GCMNetworkChannel.
+// GCMNetworkChannel needs Register to register with GCM client and obtain gcm
+// registration id. This id is used for building URL to Tango endpoint.

[tim (not reviewing), 2014/01/17 19:33:42]

nit- "cache invalidation", not "Tango".

[pavely, 2014/01/17 22:52:26]

Done.

+// It needs RequestToken and InvalidateToken to get access token to include it
+// in HTTP message to server.
+// GCMNetworkChannel lives on IO thread therefore calls will be made on IO
+// thread and callbacks should be invoked there as well.
+class GCMNetworkChannelDelegate {
+ public:
+  typedef base::Callback<void(const GoogleServiceAuthError& error,
+                              const std::string& token)> RequestTokenCallback;
+  typedef base::Callback<void(const std::string& registration_id,
+                              gcm::GCMClient::Result result)> RegisterCallback;
+
+  virtual ~GCMNetworkChannelDelegate() {}
+
+  // Request access token. Callback should be called either with access token or
+  // error code.
+  virtual void RequestToken(RequestTokenCallback callback) = 0;
+  // Invalidate access token that was rejected by server.
+  virtual void InvalidateToken(const std::string& token) = 0;
+
+  // Register with GCMProfileService. Callback should be called with either
+  // registration id or error code.
+  virtual void Register(RegisterCallback callback) = 0;
+};
+}  // namespace syncer
+
+#endif  // SYNC_NOTIFIER_GCM_NETWORK_CHANNEL_DELEGATE_H_