Certificate Transparency: Add UMA for whitelist status

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 4fd69481473431e2954fa9b5ccbb37c6646fafb8..3f6a943bb7a693922f721f5748a29a22de13d6a4 100644
--- a/tools/metrics/histograms/histograms.xml
+++ b/tools/metrics/histograms/histograms.xml
@@ -20212,6 +20212,19 @@ Therefore, the affected-histogram name has to have at least one dot in it.
   </summary>
 </histogram>
 
+<histogram name="Net.SSL_EVWhitelistValidityForNonCompliantCert" enum="Boolean">

[jwd, 2015/03/09 15:26:41]

Can you use a more precise enum type, maybe BooleanValid? Or define your own.

[Eran Messeri, 2015/03/10 21:16:35]

Done - defined my own. Can use BooleanValid if you prefer, although the name
itself is suspicious.

+  <owner>eranm@chromium.org</owner>
+  <owner>rsleevi@chromium.org</owner>
+  <summary>
+    Whether the client holds a valid EV Certificates whitelist or not. Only
+    emitted when an EV cert that is not compliant with the Certificate
+    Transparency requirement encountered.

[jwd, 2015/03/09 15:26:41]

nit: "... is encountered."

[Eran Messeri, 2015/03/10 21:16:35]

Done.

+    This histogram is intended to be short-lived and help determine if EV
+    certificates are considered non-compliant because they are not whitelisted
+    or if the client does not hold a valid instance of the whitelist.
+  </summary>
+</histogram>
+
 <histogram name="Net.SSLCertBlacklisted">
   <owner>agl@chromium.org</owner>
   <summary>