Add new histograms to confirm that PINGs are outstanding when a QUIC connection times out with open…

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 f9c317298ae8663d8078719a40ad24913bb3f245..a95be457124f478b469478c4c3b10d51b8e6ae9b 100644
--- a/tools/metrics/histograms/histograms.xml
+++ b/tools/metrics/histograms/histograms.xml
@@ -16349,6 +16349,30 @@ Therefore, the affected-histogram name has to have at least one dot in it.
   </summary>
 </histogram>
 
+<histogram name="Net.QuicSession.TimedOutWithOpenStreams.ConsecutiveRTOCount">
+  <owner>rch@chromium.org</owner>
+  <summary>
+    If a QUIC connection timed out with open streams, this contains a count of
+    consecutive RTOs.
+  </summary>
+</histogram>
+
+<histogram name="Net.QuicSession.TimedOutWithOpenStreams.ConsecutiveTLPCount">
+  <owner>rch@chromium.org</owner>
+  <summary>
+    If a QUIC connection timed out with open streams, this contains a count of
+    consecutive TLPs.
+  </summary>
+</histogram>
+
+<histogram name="Net.QuicSession.TimedOutWithOpenStreams.HasUnackedPackets">
+  <owner>rch@chromium.org</owner>
+  <summary>
+    If a QUIC connection timed out with open streams, this will be true when the
+    connection has unacked packets.
+  </summary>
+</histogram>
+
 <histogram name="Net.QuicSession.TruncatedAcksReceived">
   <owner>rch@chromium.org</owner>
   <summary>The number of truncated ACK frames received.</summary>