UMA metrics for LogDnsClient

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 fee8ffc8bb175ebd7ce9905906e441235296b34c..6adca321674df7b2d8f17ec08db6747ceaae1300 100644
--- a/tools/metrics/histograms/histograms.xml
+++ b/tools/metrics/histograms/histograms.xml
@@ -31166,10 +31166,29 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
     24 hours after the timestamp in the SCT (24 hours being the typical Maximum
     Merge Delay).
   </summary>
 </histogram>
 
+<histogram name="Net.CertificateTransparency.DnsQueryDuration" units="ms">
+  <owner>robpercival@chromium.org</owner>
+  <summary>
+    The time taken to obtain an inclusion proof from a Certificate Transparency
+    log over DNS. This includes the time taken to obtain the leaf index first.
+    Emitted at the end of an attempt.
+  </summary>
+</histogram>
+
+<histogram name="Net.CertificateTransparency.DnsQueryStatus"
+    enum="CertificateTransparencyDnsQueryStatus">
+  <owner>robpercival@chromium.org</owner>
+  <summary>
+    The status of each attempt to obtain an inclusion proof from a Certificate
+    Transparency log over DNS. This can consist of more than one DNS request.
+    Emitted at the end of an attempt.
+  </summary>
+</histogram>
+
 <histogram name="Net.CertificateTransparency.InclusionCheckResult"
     enum="CTLogEntryInclusionCheckResult">
   <owner>eranm@chromium.org</owner>
   <summary>
     The result of an inclusion check for a Certificate Transparency log entry
@@ -82185,10 +82204,18 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
     https://crbug.com/522312
   </obsolete>
   <int value="0" label="Root Certificate"/>
 </enum>
 
+<enum name="CertificateTransparencyDnsQueryStatus" type="int">
+  <int value="0" label="SUCCESS"/>
+  <int value="1" label="FAILED_UNKNOWN"/>
+  <int value="2" label="FAILED_NAME_RESOLUTION"/>
+  <int value="3" label="FAILED_LEAF_INDEX_MALFORMED"/>
+  <int value="4" label="FAILED_INCLUSION_PROOF_MALFORMED"/>
+</enum>
+
 <enum name="ChannelLayout" type="int">
   <int value="0" label="CHANNEL_LAYOUT_NONE"/>
   <int value="1" label="CHANNEL_LAYOUT_UNSUPPORTED"/>
   <int value="2" label="CHANNEL_LAYOUT_MONO"/>
   <int value="3" label="CHANNEL_LAYOUT_STEREO"/>