QUIC - added a histogram to measure the impact of reading QUIC server

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 a39b44e53533ab381bb4fa559b2f07cbafa2106c..ee61dd94ca37c65711b5c888d27563716dff75fb 100644
--- a/tools/metrics/histograms/histograms.xml
+++ b/tools/metrics/histograms/histograms.xml
@@ -10320,6 +10320,10 @@ other types of suffix sets.
   </summary>
 </histogram>
 
+<histogram name="Net.QuicServerInfo.DiskCacheReadTime" units="milliseconds">

[wtc, 2014/03/10 22:18:52]

I agree milliseconds is the right time unit for this histogram.

It seems that base::TimeDelta is in microseconds. I assume the histogram code
will convert microseconds to milliseconds for us?

[ramant (doing other things), 2014/03/10 22:26:16]

You are right.

https://code.google.com/p/chromium/codesearch#chromium/src/base/metrics/histo...


calls AddTime and AddTime converts the TimeDelta to milliseconds.


https://code.google.com/p/chromium/codesearch#chromium/src/base/metrics/stats...

[wtc, 2014/03/10 23:08:30]

Thanks, Raman. You pointed to the AddTime method of StatsCounter. But
HistogramBase::AddTime does the same conversion:

void HistogramBase::AddTime(const TimeDelta& time) {
  Add(static_cast<Sample>(time.InMilliseconds()));
}

+  <summary>Time spent to load QUIC server information from disk cache.</summary>
+</histogram>
+
 <histogram name="Net.QuicSession.CloseSessionOnError" enum="NetErrorCodes">
   <summary>
     The network error code which resulted in the session being closed.