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

content/renderer/p2p/socket_client_impl.h

Index: content/renderer/p2p/socket_client_impl.h
diff --git a/content/renderer/p2p/socket_client_impl.h b/content/renderer/p2p/socket_client_impl.h
index 4cda52ddb875d27fbd89ca38535be752e4f86859..3ce7be44dff5c3e38c433590e95c6823b3a1f168 100644
--- a/content/renderer/p2p/socket_client_impl.h
+++ b/content/renderer/p2p/socket_client_impl.h
@@ -44,10 +44,10 @@ class P2PSocketClientImpl : public P2PSocketClient {
             const std::vector<char>& data) override;
 
   // Send the |data| to the |address| using Differentiated Services Code Point
-  // |dscp|.
-  void SendWithDscp(const net::IPEndPoint& address,
-                    const std::vector<char>& data,
-                    const rtc::PacketOptions& options) override;
+  // |dscp|. Return value is the unique packet_id for this packet.
+  uint64 SendWithDscp(const net::IPEndPoint& address,
+                      const std::vector<char>& data,
+                      const rtc::PacketOptions& options) override;
 
   // Setting socket options.
   void SetOption(P2PSocketOption option, int value) override;
@@ -77,8 +77,7 @@ class P2PSocketClientImpl : public P2PSocketClient {
   void OnSocketCreated(const net::IPEndPoint& local_address,
                        const net::IPEndPoint& remote_address);
   void OnIncomingTcpConnection(const net::IPEndPoint& address);
-  void OnSendComplete(int packet_id);
-  void OnSendComplete();
+  void OnSendComplete(const P2PSendPacketMetrics& send_metrics);
   void OnError();
   void OnDataReceived(const net::IPEndPoint& address,
                       const std::vector<char>& data,
@@ -90,12 +89,19 @@ class P2PSocketClientImpl : public P2PSocketClient {
   void DeliverOnIncomingTcpConnection(
       const net::IPEndPoint& address,
       scoped_refptr<P2PSocketClient> new_client);
-  void DeliverOnSendComplete();
+  void DeliverOnSendComplete(const P2PSendPacketMetrics& send_metrics);
   void DeliverOnError();
   void DeliverOnDataReceived(const net::IPEndPoint& address,
                              const std::vector<char>& data,
                              const base::TimeTicks& timestamp);
 
+  // Helper function to be called by SendWithDscp to handle different threading
+  // condition.
+  void SendWithDscpAndPacketId(const net::IPEndPoint& address,
+                               const std::vector<char>& data,
+                               const rtc::PacketOptions& options,
+                               uint64 packet_id);
+
   // Scheduled on the IPC thread to finish initialization.
   void DoInit(P2PSocketType type,
               const net::IPEndPoint& local_address,