Detect situation when there is no missing send completion signal in P2PSocket implementation.

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 332d93c8755688078549034e4ec41dcb0eb06c7e..8a0a3f9967b5c9452f37c1eb528098e6ae8715ac 100644
--- a/tools/metrics/histograms/histograms.xml
+++ b/tools/metrics/histograms/histograms.xml
@@ -40191,6 +40191,16 @@ Therefore, the affected-histogram name has to have at least one dot in it.
   </summary>
 </histogram>
 
+<histogram name="WebRTC.ApplicationSocketMismatchPacketsDetected"
+    enum="BooleanDetected">
+  <owner>guoweis@chromium.org</owner>
+  <summary>
+    This counter detects the condition when a packet is sent from the
+    application layer down to the system but has never received the completion
+    signal for that packet to increment the send_bytes_available.
+  </summary>
+</histogram>
+
 <histogram name="WebRTC.AudioCaptureTime" units="milliseconds">
   <obsolete>
     Removed from code 2014/2/25.
@@ -41625,6 +41635,11 @@ Therefore, the affected-histogram name has to have at least one dot in it.
   <int value="1" label="Deleted"/>
 </enum>
 
+<enum name="BooleanDetected" type="int">
+  <int value="0" label="Not detected"/>
+  <int value="1" label="Detected"/>
+</enum>
+
 <enum name="BooleanDidEvict" type="int">
   <int value="0" label="Did not evict"/>
   <int value="1" label="Did evict"/>
@@ -57802,6 +57817,7 @@ 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.ApplicationSocketMismatchPacketsDetected"/>
   <affected-histogram name="WebRTC.SystemMaxConsecutiveBytesDelayed"/>
   <affected-histogram name="WebRTC.SystemPercentPacketsDelayed"/>
   <affected-histogram name="WebRTC.SystemSendPacketDuration"/>