[GCM] API update to allow only a single sender in registration

google_apis/gcm/gcm_client_impl.cc

Index: google_apis/gcm/gcm_client_impl.cc
diff --git a/google_apis/gcm/gcm_client_impl.cc b/google_apis/gcm/gcm_client_impl.cc
index 46b246d3a4baa06ae65b422acd2cf8382f3d73f6..3418433c9c5ce314efbd1e14b4f084fc289a469c 100644
--- a/google_apis/gcm/gcm_client_impl.cc
+++ b/google_apis/gcm/gcm_client_impl.cc
@@ -298,14 +298,14 @@ void GCMClientImpl::CheckOut() {
 
 void GCMClientImpl::Register(const std::string& app_id,
                              const std::string& cert,
-                             const std::vector<std::string>& sender_ids) {
+                             const std::string& sender_id) {
   DCHECK_EQ(state_, READY);
   RegistrationRequest::RequestInfo request_info(
       device_checkin_info_.android_id,
       device_checkin_info_.secret,
       app_id,
       cert,
-      sender_ids);
+      sender_id);
   DCHECK_EQ(0u, pending_registrations_.count(app_id));
 
   RegistrationRequest* registration_request =