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 523d6b06d3a68965a6b790958008c57f958ab91a..9b670f5ecafe473e807165db9fdc58e5983aab11 100644
--- a/tools/metrics/histograms/histograms.xml
+++ b/tools/metrics/histograms/histograms.xml
@@ -28896,6 +28896,13 @@ Therefore, the affected-histogram name has to have at least one dot in it.
   </summary>
 </histogram>
 
+<histogram name="Process.Sandbox.Lowbox.Launch.Error" units="GetLastError">

[Ilya Sherman, 2015/03/19 21:35:11]

Please associate an enum rather than just writing "GetLastError" in the units. 
The enum doesn't have to be comprehensive; but if it isn't, please include a
link to where uncovered errors can be decoded.

[Shrikant Kelkar, 2015/03/19 21:40:50]

We don't know what is range of error values here. I can include link to decode
values though
(https://msdn.microsoft.com/en-us/library/windows/desktop/ms681381(v=vs.85).aspx)
and there is possibility that the error doesn't fall in documented error codes
in this particular situation as the API is new. Wondering if I should still use
enums vs units? I used units="GetLastError" following example of
PlatformFile.UnknownErrors.Windows.

[Ilya Sherman, 2015/03/19 21:43:08]

Please associate an enum rather than just writing "GetLastError" in the units. 
The enum doesn't have to be comprehensive; but if it isn't, please include a
link to where uncovered errors can be decoded.

[Ilya Sherman, 2015/03/19 21:43:08]

I see -- there are a *ton* of possible error messages.  Okay, in that case,
please just include a link to the list.  Thanks.

+  <owner>shrikant@chromium.org</owner>
+  <summary>
+    Errors returned while launching lowbox enabled sandboxed process on Windows.
+  </summary>
+</histogram>
+
 <histogram name="Profile.AddNewUser" enum="ProfileAddNewUser">
   <owner>bcwhite@chromium.org</owner>
   <owner>rlp@chromium.org</owner>