Fix net_unittests when run in a virtualenv.

net/test/python_utils.h

Index: net/test/python_utils.h
diff --git a/net/test/python_utils.h b/net/test/python_utils.h
index c72c9445dcbc456c4ea1251bc162fce9e9df965c..aba4addddcacf6c1a63ee1672d55808f6d8deee8 100644
--- a/net/test/python_utils.h
+++ b/net/test/python_utils.h
@@ -24,6 +24,9 @@ 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;