Add instrumentation to track the IceCandidatePairType and IceConnectionState

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 92f3722c60215bd3cc1ce5c425f3295f61d48d43..d6ae25fbf0cc5751d6e3db392d825b65b951cc8d 100644
--- a/tools/metrics/histograms/histograms.xml
+++ b/tools/metrics/histograms/histograms.xml
@@ -50664,6 +50664,24 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
   </summary>
 </histogram>
 
+<histogram name="WebRTC.PeerConnection.CandidatePairType"
+    enum="IceCandidatePairTypes">
+  <owner>guoweis@chromium.org</owner>
+  <summary>
+    Counters of various ICE Endpoint types. These values are logged for the
+    first BestConnection of a PeerConnection.

[pthatcher2, 2015/08/19 02:59:06]

BestConnection => selected candidate pair

[guoweis_left_chromium, 2015/08/19 18:42:49]

Done.

+  </summary>
+</histogram>
+
+<histogram name="WebRTC.PeerConnection.ConnectionState"
+    enum="IceConnectionStates">
+  <owner>guoweis@chromium.org</owner>
+  <summary>
+    Counters of ICE Connection states. These values are logged when the
+    PeerConnection gets into that state for the first time.

[pthatcher2, 2015/08/19 02:59:06]

Or after an ICE restart?  Whichever we decide, we should make the comment match
the measurement.

[guoweis_left_chromium, 2015/08/19 18:42:49]

Done.

+  </summary>
+</histogram>
+
 <histogram name="WebRTC.PeerConnection.IPMetrics" enum="PeerConnectionCounters">
   <owner>mallinath@chromium.org</owner>
   <summary>
@@ -60901,6 +60919,34 @@ http://cs/file:chrome/histograms.xml - but prefer this file for new entries.
   <int value="2" label="REUSED_IDLE">previously used (keep-alive?) socket</int>
 </enum>
 
+<enum name="IceCandidatePairTypes" type="int">
+  <int value="0" label="host_host"/>
+  <int value="1" label="host_srflx"/>
+  <int value="2" label="host_relay"/>
+  <int value="3" label="host_prflx"/>
+  <int value="4" label="srflx_host"/>
+  <int value="5" label="srflx_srflx"/>
+  <int value="6" label="srflx_relay"/>
+  <int value="7" label="srflx_prflx"/>
+  <int value="8" label="relay_host"/>
+  <int value="9" label="relay_srflx"/>
+  <int value="10" label="relay_relay"/>
+  <int value="11" label="relay_prflx"/>
+  <int value="12" label="prflx_host"/>
+  <int value="13" label="prflx_srflx"/>
+  <int value="14" label="prflx_relay"/>
+</enum>
+
+<enum name="IceConnectionStates" type="int">
+  <int value="0" label="IceConnectionNew"/>
+  <int value="1" label="IceConnectionChecking"/>
+  <int value="2" label="IceConnectionConnected"/>
+  <int value="3" label="IceconnectionCompleted"/>
+  <int value="4" label="IceconnectionFailed"/>
+  <int value="5" label="IceconnectionDisconnected"/>
+  <int value="6" label="IceconnectionClosed"/>
+</enum>
+
 <enum name="IDBContextForcedCloseReason" type="int">
   <int value="0" label="DeleteOrigin">
     A request was made to delete the data for an origin.
@@ -74336,6 +74382,7 @@ To add a new entry, add it with any value and run test to compute valid value.
 <histogram_suffixes name="IPProtocolType" separator="_">
   <suffix name="UDP"/>
   <suffix name="TCP"/>
+  <affected-histogram name="WebRTC.PeerConnection.CandidatePairType"/>
   <affected-histogram name="WebRTC.SystemMaxConsecutiveBytesDelayed"/>
   <affected-histogram name="WebRTC.SystemPercentPacketsDelayed"/>
   <affected-histogram name="WebRTC.SystemSendPacketDuration"/>