Fix preconnect crash when we hit max socket limit.

net/socket/client_socket_pool_base.h

 // Copyright (c) 2010 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.
 //
 // A ClientSocketPoolBase is used to restrict the number of sockets open at
 // a time.  It also maintains a list of idle persistent sockets for reuse.
 // Subclasses of ClientSocketPool should compose ClientSocketPoolBase to handle
 // the core logic of (1) restricting the number of active (connected or
 // connecting) sockets per "group" (generally speaking, the hostname), (2)
 // maintaining a per-group list of idle, persistent sockets for reuse, and (3)
@@ skipping 462 matching lines @@
   static void LogBoundConnectJobToRequest(
       const NetLog::Source& connect_job_source, const Request* request);
 
   // Closes one idle socket.  Picks the first one encountered.
   // TODO(willchan): Consider a better algorithm for doing this.  Perhaps we
   // should keep an ordered list of idle sockets, and close them in order.
   // Requires maintaining more state.  It's not clear if it's worth it since
   // I'm not sure if we hit this situation often.
   void CloseOneIdleSocket();
 
+  // Same as CloseOneIdleSocket() except it won't close an idle socket in
+  // |group|.  If |group| is NULL, it is ignored.  Returns true if it closed a
+  // socket.
+  bool CloseOneIdleSocketExceptInGroup(const Group* group);
+
   // Checks if there are stalled socket groups that should be notified
   // for possible wakeup.
   void CheckForStalledSocketGroups();
 
   // Posts a task to call InvokeUserCallback() on the next iteration through the
   // current message loop.  Inserts |callback| into |pending_callback_map_|,
   // keyed by |handle|.
   void InvokeUserCallbackLater(
       ClientSocketHandle* handle, CompletionCallback* callback, int rv);
 
@@ skipping 238 matching lines @@
   // Histograms for the pool
   ClientSocketPoolHistograms* const histograms_;
   internal::ClientSocketPoolBaseHelper helper_;
 
   DISALLOW_COPY_AND_ASSIGN(ClientSocketPoolBase);
 };
 
 }  // namespace net
 
 #endif  // NET_SOCKET_CLIENT_SOCKET_POOL_BASE_H_