Implement UMA and internal data structure for tracking EWOULDBLOCK.

content/browser/renderer_host/p2p/socket_host.cc

Index: content/browser/renderer_host/p2p/socket_host.cc
diff --git a/content/browser/renderer_host/p2p/socket_host.cc b/content/browser/renderer_host/p2p/socket_host.cc
index 1693918bd32854572a8b085efa8b434cb61a3238..34dbbdf67a8104fe0c7c0b3a9ca3b17f80a2e2e1 100644
--- a/content/browser/renderer_host/p2p/socket_host.cc
+++ b/content/browser/renderer_host/p2p/socket_host.cc
@@ -4,6 +4,7 @@
 
 #include "content/browser/renderer_host/p2p/socket_host.h"
 
+#include "base/metrics/histogram.h"
 #include "base/sys_byteorder.h"
 #include "content/browser/renderer_host/p2p/socket_host_tcp.h"
 #include "content/browser/renderer_host/p2p/socket_host_tcp_server.h"
@@ -460,10 +461,21 @@ P2PSocketHost::P2PSocketHost(IPC::Sender* message_sender, int socket_id)
       state_(STATE_UNINITIALIZED),
       dump_incoming_rtp_packet_(false),
       dump_outgoing_rtp_packet_(false),
-      weak_ptr_factory_(this) {
+      weak_ptr_factory_(this),
+      send_queue_length_max_(0),
+      protocol_type_(P2PSocketHost::UNKNOWN) {
 }
 
-P2PSocketHost::~P2PSocketHost() { }
+P2PSocketHost::~P2PSocketHost() {
+  DCHECK(protocol_type_ != P2PSocketHost::UNKNOWN);
+  if (protocol_type_ == P2PSocketHost::UDP) {
+    UMA_HISTOGRAM_COUNTS_100("WebRTC.MaxSystemConsecutiveEWB_UDP",
+                             send_queue_length_max_);
+  } else {
+    UMA_HISTOGRAM_COUNTS_100("WebRTC.MaxSystemConsecutiveEWB_TCP",
+                             send_queue_length_max_);
+  }
+}
 
 // Verifies that the packet |data| has a valid STUN header.
 // static