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

content/renderer/p2p/socket_client.h

Index: content/renderer/p2p/socket_client.h
diff --git a/content/renderer/p2p/socket_client.h b/content/renderer/p2p/socket_client.h
index d92407cd5c9bf1e6fa83564e8d642449d06c0028..f9f2c4e543f33bb031c0d4eab6e0e20f0d5324f1 100644
--- a/content/renderer/p2p/socket_client.h
+++ b/content/renderer/p2p/socket_client.h
@@ -41,10 +41,10 @@ class P2PSocketClient : public base::RefCountedThreadSafe<P2PSocketClient> {
                     const std::vector<char>& data) = 0;
 
   // Send the |data| to the |address| using Differentiated Services Code Point
-  // |dscp|.
-  virtual void SendWithDscp(const net::IPEndPoint& address,
-                            const std::vector<char>& data,
-                            const rtc::PacketOptions& options) = 0;
+  // |dscp|. Return value is the unique packet_id for this packet.
+  virtual uint64 SendWithDscp(const net::IPEndPoint& address,
+                              const std::vector<char>& data,
+                              const rtc::PacketOptions& options) = 0;
 
   virtual void SetOption(P2PSocketOption option, int value) = 0;