Add data usage tracking for GAIA auth api and GCM engine service

google_apis/gaia/gaia_auth_fetcher.cc

Index: google_apis/gaia/gaia_auth_fetcher.cc
diff --git a/google_apis/gaia/gaia_auth_fetcher.cc b/google_apis/gaia/gaia_auth_fetcher.cc
index 0940d3c8ea0fecb16cbe6e85b195622f580ef2eb..6dff7350cc1756ffbe55b40a59375b6ec075a66b 100644
--- a/google_apis/gaia/gaia_auth_fetcher.cc
+++ b/google_apis/gaia/gaia_auth_fetcher.cc
@@ -16,6 +16,7 @@
 #include "base/strings/string_util.h"
 #include "base/strings/stringprintf.h"
 #include "base/values.h"
+#include "components/data_use_measurement/core/data_use_user_data.h"
 #include "google_apis/gaia/gaia_auth_consumer.h"
 #include "google_apis/gaia/gaia_constants.h"
 #include "google_apis/gaia/gaia_urls.h"
@@ -227,6 +228,8 @@ void GaiaAuthFetcher::CreateAndStartGaiaFetcher(const std::string& body,
       this);
   fetcher_->SetRequestContext(getter_);
   fetcher_->SetUploadData("application/x-www-form-urlencoded", body);
+  data_use_measurement::DataUseUserData::AttachToFetcher(
+      fetcher_.get(), data_use_measurement::DataUseUserData::GAIA_AUTH_FETCHER);
 
   VLOG(2) << "Gaia fetcher URL: " << gaia_gurl.spec();
   VLOG(2) << "Gaia fetcher headers: " << headers;