split file path constants out for split link

This is a follow on of work started in https://codereview.chromium.org/15310002/

TBR=brettw@chromium.org
R=cpu@chromium.org
BUG=237249

Review URL: https://chromiumcodereview.appspot.com/15495003

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@201279 0039d316-1c4b-4281-b951-d872f2087c98


CrOS-Libchrome-Original-Commit: f39e0381ea6e83c74d149fd3afda84dbf64a1681
diff --git a/base/files/file_path.h b/base/files/file_path.h
index d66d631..d7e134e 100644
--- a/base/files/file_path.h
+++ b/base/files/file_path.h
@@ -150,6 +150,9 @@
   // when composing pathnames.
   static const CharType kSeparators[];
 
+  // arraysize(kSeparators).
+  static const size_t kSeparatorsLength;
+
   // A special path component meaning "this directory."
   static const CharType kCurrentDirectory[];