Move string_number_conversions to base/strings.

This only updates includes in base and keeps a forwarding header for now to keep the change under control.

BUG=

Review URL: https://codereview.chromium.org/12092078

git-svn-id: svn://svn.chromium.org/chrome/trunk/src@181161 0039d316-1c4b-4281-b951-d872f2087c98
diff --git a/base/version.cc b/base/version.cc
index b7db4b5..2364c6d 100644
--- a/base/version.cc
+++ b/base/version.cc
@@ -7,9 +7,9 @@
 #include <algorithm>
 
 #include "base/logging.h"
-#include "base/string_number_conversions.h"
 #include "base/string_split.h"
 #include "base/string_util.h"
+#include "base/strings/string_number_conversions.h"
 
 namespace {