QUIC - Track how long proof verification takes when cached server config

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 8edba605650c584b134a7fddb92a1fb7122f4d70..9b79925c70f131c92c73fc7ab36faaf8d53b5211 100644
--- a/tools/metrics/histograms/histograms.xml
+++ b/tools/metrics/histograms/histograms.xml
@@ -26096,17 +26096,7 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
 
 <histogram name="Net.QuicSession.VerifyProofTime" units="milliseconds">
   <owner>rtenneti@chromium.org</owner>
-  <summary>
-    Time spent verifying the signature and certificate chain of a server.
-  </summary>
-</histogram>
-
-<histogram name="Net.QuicSession.VerifyProofTime.google" units="milliseconds">
-  <owner>rtenneti@chromium.org</owner>
-  <summary>
-    Time spent verifying the signature and certificate chain for www.google.com
-    server.
-  </summary>
+  <summary>Time spent verifying the signature and certificate chain</summary>

[Alexei Svitkine (slow), 2016/01/06 18:59:02]

Nit: Make it a full sentence (add .). Mention when this is logged.

[ramant (doing other things), 2016/01/06 19:20:11]

Done.

 </histogram>
 
 <histogram name="Net.QuicSession.WriteError" enum="NetErrorCodes">
@@ -84729,6 +84719,14 @@ To add a new entry, add it with any value and run test to compute valid value.
   <affected-histogram name="Net.QuicSession.Connect"/>
 </histogram_suffixes>
 
+<histogram_suffixes name="QuicSessionVerifyProofTime" separator=".">
+  <suffix name="" label="of a server."/>
+  <suffix name="google" label="for www.google.com server."/>
+  <suffix name="CachedServerConfig"
+      label="of a server when server config from cache is used."/>
+  <affected-histogram name="Net.QuicSession.VerifyProofTime"/>
+</histogram_suffixes>
+
 <histogram_suffixes name="RemoteProcessWarmStartFast" separator="">
   <suffix name="" label="Normal start."/>
   <suffix name="Fast"