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

subprocess.cc

 // Copyright (c) 2009 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #include "update_engine/subprocess.h"
 #include <stdlib.h>
 #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"
 
 using std::string;
 using std::vector;
 
 namespace chromeos_update_engine {
 
 void Subprocess::GChildExitedCallback(GPid pid, gint status, gpointer data) {
   COMPILE_ASSERT(sizeof(guint) == sizeof(uint32_t),
@@ skipping 121 matching lines @@
   if (child_stdout)
     LOG(INFO) << "Postinst stdout:" << child_stdout;
   if (child_stderr)
     LOG(INFO) << "Postinst stderr:" << child_stderr;
   return success;
 }
 
 Subprocess* Subprocess::subprocess_singleton_ = NULL;
 
 }  // namespace chromeos_update_engine