Made setting lowbox token a warning.

tools/metrics/histograms/histograms.xml

Index: tools/metrics/histograms/histograms.xml
diff --git a/tools/metrics/histograms/histograms.xml b/tools/metrics/histograms/histograms.xml
index c7aadfd4de6be6c556ce8487c5729308b8a79f8c..e6c54a9130d1a992655bbaf0a2f2a117010e3b4b 100644
--- a/tools/metrics/histograms/histograms.xml
+++ b/tools/metrics/histograms/histograms.xml
@@ -43754,6 +43754,23 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
   </summary>
 </histogram>
 
+<histogram name="Process.Sandbox.Launch.Warning" units="GetLastError">
+  <owner>forshaw@chromium.org</owner>
+  <summary>
+    Warnings returned while launching sandboxed process on Windows. For decoding
+    error code please refer to http://goo.gl/fJJiAv.

[Will Harris, 2016/07/12 16:10:59]

explain exactly when these are both logged

+  </summary>
+</histogram>
+
+<histogram name="Process.Sandbox.Launch.WarningResultCode"
+    units="LaunchErrorCodes">
+  <owner>forshaw@chromium.org</owner>
+  <summary>
+    The warning launch error returned while launching sandboxed process on
+    Windows.
+  </summary>
+</histogram>
+
 <histogram name="Process.Sandbox.Lowbox.Launch.Error" units="GetLastError">
   <owner>shrikant@chromium.org</owner>
   <summary>