Fix preconnect crash when we hit max socket limit.

net/socket/client_socket_pool_base.cc

Index: net/socket/client_socket_pool_base.cc
diff --git a/net/socket/client_socket_pool_base.cc b/net/socket/client_socket_pool_base.cc
index 02ac58710b5a6e52abbd4ef3c2d5bb7c0dbb4bbd..b08d1c87717d5b1ebd69a160a8f7a6a95bb2e1c5 100644
--- a/net/socket/client_socket_pool_base.cc
+++ b/net/socket/client_socket_pool_base.cc
@@ -286,7 +286,9 @@ int ClientSocketPoolBaseHelper::RequestSocketInternal(
 
   if (ReachedMaxSocketsLimit()) {
     if (idle_socket_count() > 0) {
-      CloseOneIdleSocket();
+      bool closed = CloseOneIdleSocketExceptInGroup(group);
+      if (preconnecting && !closed)
+        return ERR_PRECONNECT_MAX_SOCKET_LIMIT;
     } else {
       // We could check if we really have a stalled group here, but it requires
       // a scan of all groups, so just flip a flag here, and do the check later.
@@ -928,10 +930,17 @@ bool ClientSocketPoolBaseHelper::ReachedMaxSocketsLimit() const {
 }
 
 void ClientSocketPoolBaseHelper::CloseOneIdleSocket() {
+  CloseOneIdleSocketExceptInGroup(NULL);
+}
+
+bool ClientSocketPoolBaseHelper::CloseOneIdleSocketExceptInGroup(
+    const Group* exception_group) {
   CHECK_GT(idle_socket_count(), 0);
 
   for (GroupMap::iterator i = group_map_.begin(); i != group_map_.end(); ++i) {
     Group* group = i->second;
+    if (exception_group == group)
+      continue;
     std::list<IdleSocket>* idle_sockets = group->mutable_idle_sockets();
 
     if (!idle_sockets->empty()) {
@@ -941,11 +950,14 @@ void ClientSocketPoolBaseHelper::CloseOneIdleSocket() {
       if (group->IsEmpty())
         RemoveGroup(i);
 
-      return;
+      return true;
     }
   }
 
-  LOG(DFATAL) << "No idle socket found to close!.";
+  if (!exception_group)
+    LOG(DFATAL) << "No idle socket found to close!.";
+
+  return false;
 }
 
 void ClientSocketPoolBaseHelper::InvokeUserCallbackLater(