Added three histograms to track the following TCP connection latency

net/socket/transport_client_socket_pool.h

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef NET_SOCKET_TRANSPORT_CLIENT_SOCKET_POOL_H_
 #define NET_SOCKET_TRANSPORT_CLIENT_SOCKET_POOL_H_
 
 #include <string>
 
 #include "base/basictypes.h"
@@ skipping 75 matching lines @@
 
  private:
   enum State {
     STATE_RESOLVE_HOST,
     STATE_RESOLVE_HOST_COMPLETE,
     STATE_TRANSPORT_CONNECT,
     STATE_TRANSPORT_CONNECT_COMPLETE,
     STATE_NONE,
   };
 
+  enum ConnectInterval {
+    CONNECT_INTERVAL_LE_10MS,
+    CONNECT_INTERVAL_LE_20MS,
+    CONNECT_INTERVAL_GT_20MS,
+  };
+
   void OnIOComplete(int result);
 
   // Runs the state transition loop.
   int DoLoop(int result);
 
   int DoResolveHost();
   int DoResolveHostComplete(int result);
   int DoTransportConnect();
   int DoTransportConnectComplete(int result);
 
@@ skipping 12 matching lines @@
   AddressList addresses_;
   State next_state_;
 
   scoped_ptr<StreamSocket> transport_socket_;
 
   scoped_ptr<StreamSocket> fallback_transport_socket_;
   scoped_ptr<AddressList> fallback_addresses_;
   base::TimeTicks fallback_connect_start_time_;
   base::OneShotTimer<TransportConnectJob> fallback_timer_;
 
-  // If the interval between this connect and previous connect is less than
-  // 20ms, then |less_than_20ms_since_connect_| is set to true.
-  bool less_than_20ms_since_connect_;
+  // Track the interval between this connect and previous connect.
+  ConnectInterval interval_between_connects_;
 
   DISALLOW_COPY_AND_ASSIGN(TransportConnectJob);
 };
 
 class NET_EXPORT_PRIVATE TransportClientSocketPool : public ClientSocketPool {
  public:
   typedef TransportSocketParams SocketParams;
 
   TransportClientSocketPool(
       int max_sockets,
@@ skipping 74 matching lines @@
   };
 
   PoolBase base_;
 
   DISALLOW_COPY_AND_ASSIGN(TransportClientSocketPool);
 };
 
 }  // namespace net
 
 #endif  // NET_SOCKET_TRANSPORT_CLIENT_SOCKET_POOL_H_