Introduce system_info as an independent container.

athena/util/athena_constants.cc

Index: athena/util/athena_constants.cc
diff --git a/athena/content/shell/web_activity_helpers.cc b/athena/util/athena_constants.cc
similarity index 64%
copy from athena/content/shell/web_activity_helpers.cc
copy to athena/util/athena_constants.cc
index f5c1d90c0768d697f9c68e665fd9dfcb76fc9791..96c7b09ddfc78349a0513282d4635415d9f6cd23 100644
--- a/athena/content/shell/web_activity_helpers.cc
+++ b/athena/util/athena_constants.cc
@@ -2,11 +2,10 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-#include "athena/content/web_activity_helpers.h"
+#include "athena/util/athena_constants.h"
 
 namespace athena {
 
-void AttachWebActivityHelpers(content::WebContents* contents) {
-}
+const int kSystemUIHeight = 24;
 
 }  // namespace athena