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

google_apis/gaia/oauth2_access_token_fetcher_impl.cc

Index: google_apis/gaia/oauth2_access_token_fetcher_impl.cc
diff --git a/google_apis/gaia/oauth2_access_token_fetcher_impl.cc b/google_apis/gaia/oauth2_access_token_fetcher_impl.cc
index 267388f9f8c60ae80535624ce552840015e58be4..5ef55dd91d2efbe4bbfb38996844a8a3833342f6 100644
--- a/google_apis/gaia/oauth2_access_token_fetcher_impl.cc
+++ b/google_apis/gaia/oauth2_access_token_fetcher_impl.cc
@@ -15,6 +15,7 @@
 #include "base/strings/stringprintf.h"
 #include "base/time/time.h"
 #include "base/values.h"
+#include "components/data_use_measurement/core/data_use_user_data.h"
 #include "google_apis/gaia/gaia_urls.h"
 #include "google_apis/gaia/google_service_auth_error.h"
 #include "net/base/escape.h"
@@ -101,6 +102,8 @@ static std::unique_ptr<URLFetcher> CreateFetcher(
   result->SetRequestContext(getter);
   result->SetLoadFlags(net::LOAD_DO_NOT_SEND_COOKIES |
                        net::LOAD_DO_NOT_SAVE_COOKIES);
+  data_use_measurement::DataUseUserData::AttachToFetcher(
+      result.get(), data_use_measurement::DataUseUserData::GAIA_AUTH_FETCHER);
   // Fetchers are sometimes cancelled because a network change was detected,
   // especially at startup and after sign-in on ChromeOS. Retrying once should
   // be enough in those cases; let the fetcher retry up to 3 times just in case.