[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/extent_writer.h b/extent_writer.h
index ac36364..5eda364 100644
--- a/extent_writer.h
+++ b/extent_writer.h
@@ -6,7 +6,7 @@
 #define CHROMEOS_PLATFORM_UPDATE_ENGINE_EXTENT_WRITER_H__
 
 #include <vector>
-#include "chromeos/obsolete_logging.h"
+#include "base/logging.h"
 #include "update_engine/update_metadata.pb.h"
 #include "update_engine/utils.h"