Add a dedicated SSL protocol version metric.

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 bce02858fd55fc9c939193d3659665cc0ac299a1..2b3cea65cd046e118e197d034d717a07f73abd34 100644
--- a/tools/metrics/histograms/histograms.xml
+++ b/tools/metrics/histograms/histograms.xml
@@ -16266,7 +16266,7 @@ Therefore, the affected-histogram name has to have at least one dot in it.
 </histogram>
 
 <histogram name="Net.ConnectionTypeCount3" enum="ConnectionType">
-  <owner>Please list the metric's owners. Add more owner tags as needed.</owner>
+  <owner>davidben@chromium.org</owner>
   <summary>
     Each bucket is the number of successful connections of a particular type
     that the user has had during the session.
@@ -17261,7 +17261,7 @@ Therefore, the affected-histogram name has to have at least one dot in it.
 </histogram>
 
 <histogram name="Net.HadConnectionType3" enum="ConnectionType">
-  <owner>Please list the metric's owners. Add more owner tags as needed.</owner>
+  <owner>davidben@chromium.org</owner>
   <summary>
     Each bucket is a boolean (0 or 1) indicating whether the user has had a
     successful connection of that type during the session.
@@ -19721,6 +19721,11 @@ Therefore, the affected-histogram name has to have at least one dot in it.
   </summary>
 </histogram>
 
+<histogram name="Net.SSL_Version" enum="SSLOrQUICVersion">

[Ilya Sherman, 2015/02/19 20:18:35]

Nit: Please use CamelCase, i.e. no underscore in "SSLVersion".

[davidben, 2015/02/19 21:22:34]

Done. (I was wondering which was the right convention... //net's got a mix.)

+  <owner>davidben@chromium.org</owner>
+  <summary>The SSL/TLS version that was negotiated.</summary>

[Ilya Sherman, 2015/02/19 20:18:35]

Please document when this is recorded.

[davidben, 2015/02/19 21:22:34]

Done. Also added to the metric I copied this text from.

+</histogram>
+
 <histogram name="Net.SSLCertBlacklisted">
   <owner>agl@chromium.org</owner>
   <summary>
@@ -58447,6 +58452,17 @@ To add a new entry, add it with any value and run test to compute valid value.
   <int value="3" label="NOT_EXPIRED_AND_DO_NOT_PROCEED"/>
 </enum>
 
+<enum name="SSLOrQUICVersion" type="int">
+  <summary>SSL/TLS protocol versions</summary>

[Ilya Sherman, 2015/02/19 20:18:35]

nit: You can leave this summary if you want to, but it's not really going to be
shown on the dashboard (except on mouse hover).  Most enums omit a summary.

[davidben, 2015/02/19 21:22:34]

Done.

+  <int value="0">Unknown</int>

[Ilya Sherman, 2015/02/19 20:18:35]

nit: Please use label attributes.  As you've written it, the dashboard would
list values 0-7, and strings like "Unknown" would be shown only on hover.

[davidben, 2015/02/19 21:22:34]

Oops. Not sure where I got that spelling from. Done.

+  <int value="1">SSL 2.0</int>
+  <int value="2">SSL 3.0</int>
+  <int value="3">TLS 1.0</int>
+  <int value="4">TLS 1.1</int>
+  <int value="5">TLS 1.2</int>
+  <int value="7">QUIC</int>

[Ilya Sherman, 2015/02/19 20:18:35]

What happened to value 6?

[davidben, 2015/02/19 21:22:34]

It's apparently reserved for TLS 1.3 but not actually allocated yet? Yeah, I
dunno. I didn't write that kooky enum.

https://code.google.com/p/chromium/codesearch#chromium/src/net/ssl/ssl_connec...

+</enum>
+
 <enum name="SSLProtocolNegotiation" type="int">
   <int value="1" label="ALPN, HTTP/1.1"/>
   <int value="100" label="ALPN, SPDY 2.0"/>