Fix net_unittests when run in a virtualenv.

net/test/python_utils.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.
 
 #ifndef NET_TEST_PYTHON_UTILS_H_
 #define NET_TEST_PYTHON_UTILS_H_
 
 #include "base/compiler_specific.h"
 
 namespace base {
 class CommandLine;
 class FilePath;
 }
 
 // This is the python path variable name.
 extern const char kPythonPathEnv[];
 
 // Clears the python path, this is useful for test hermeticity.
 void ClearPythonPath();
 
 // Appends the dir to python path environment variable.
 void AppendToPythonPath(const base::FilePath& dir);
 
 // Return the location of the compiler-generated python protobuf.
 bool GetPyProtoPath(base::FilePath* dir);
 
+// Returns if a virtualenv is currently active.
+bool IsInPythonVirtualEnv();
+
 // Returns the command that should be used to launch Python.
 bool GetPythonCommand(base::CommandLine* python_cmd) WARN_UNUSED_RESULT;
 
 #endif  // NET_TEST_PYTHON_UTILS_H_