[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/subprocess.cc b/subprocess.cc
index 696779f..c319a22 100755
--- a/subprocess.cc
+++ b/subprocess.cc
@@ -7,7 +7,7 @@
 #include <string.h>
 #include <string>
 #include <vector>
-#include "chromeos/obsolete_logging.h"
+#include "base/logging.h"
 #include "base/scoped_ptr.h"
 #include "base/string_util.h"