update_engine: Rename "chromeos" -> "brillo" in include paths and namespaces

libchromeos is transitioning to libbrillo and chromeos namespaces
and include directory is changing to brillo.

Bug: 24872993
Change-Id: I770659a95be380a50fe3b2ba9f91d65818f40945
diff --git a/update_manager/real_config_provider.cc b/update_manager/real_config_provider.cc
index 1713320..ebaac75 100644
--- a/update_manager/real_config_provider.cc
+++ b/update_manager/real_config_provider.cc
@@ -18,13 +18,13 @@
 
 #include <base/files/file_path.h>
 #include <base/logging.h>
-#include <chromeos/key_value_store.h>
+#include <brillo/key_value_store.h>
 
 #include "update_engine/constants.h"
 #include "update_engine/update_manager/generic_variables.h"
 #include "update_engine/utils.h"
 
-using chromeos::KeyValueStore;
+using brillo::KeyValueStore;
 
 namespace {