update_engine: Update libchrome APIs to r369476

The new libchrome has been ported from Chromium and some APIs have
changed. Make necessary changes at call sites.

Change-Id: I42e65bda7f1dbdf6f6e0ebf356d2cfea6b729193
diff --git a/omaha_response.h b/omaha_response.h
index 3a5a889..60ec4ac 100644
--- a/omaha_response.h
+++ b/omaha_response.h
@@ -78,7 +78,7 @@
   // aka "Pacific Time".)
   int install_date_days = -1;
 };
-COMPILE_ASSERT(sizeof(off_t) == 8, off_t_not_64bit);
+static_assert(sizeof(off_t) == 8, "off_t not 64 bit");
 
 }  // namespace chromeos_update_engine