[update_engine] Update to use not-hideously-old logging API from chrome

BUG=None
TEST=compile

Change-Id: Ieed8952b6806a72b59e16c1579f7293b6a98157a

Review URL: http://codereview.chromium.org/3170010
diff --git a/tarjan_unittest.cc b/tarjan_unittest.cc
index 9c4d7a8..a9f2c8b 100644
--- a/tarjan_unittest.cc
+++ b/tarjan_unittest.cc
@@ -4,7 +4,7 @@
 
 #include <utility>
 #include <gtest/gtest.h>
-#include "chromeos/obsolete_logging.h"
+#include "base/logging.h"
 #include "update_engine/graph_types.h"
 #include "update_engine/tarjan.h"
 #include "update_engine/utils.h"