Extract GCMClient data types into separate gcm_types.h

sync/notifier/gcm_network_channel_delegate.h

Index: sync/notifier/gcm_network_channel_delegate.h
diff --git a/sync/notifier/gcm_network_channel_delegate.h b/sync/notifier/gcm_network_channel_delegate.h
index 36485a19293c762eb6fb4f59651cfac9be75a133..5dd1c85b8deea2c4f9f3065077dc31eac0d835b2 100644
--- a/sync/notifier/gcm_network_channel_delegate.h
+++ b/sync/notifier/gcm_network_channel_delegate.h
@@ -27,7 +27,7 @@ class GCMNetworkChannelDelegate {
   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;
+                              gcm::Result result)> RegisterCallback;
   typedef base::Callback<void(const std::string& message,
                               const std::string& echo_token)> MessageCallback;