Add "run_testserver --sync-test" for easy chromiumsync_test.py launching.

net/test/test_server_posix.cc

Index: net/test/test_server_posix.cc
diff --git a/net/test/test_server_posix.cc b/net/test/test_server_posix.cc
index f15acc3b84d0dfb30f32381a709c232caf2fb9d5..73509f8ec63e721c7c610f0876bec0263b031af8 100644
--- a/net/test/test_server_posix.cc
+++ b/net/test/test_server_posix.cc
@@ -93,8 +93,13 @@ bool ReadData(int fd, ssize_t bytes_max, uint8* buffer,
 
 namespace net {
 
+// static
+FilePath TestServer::GetAbsolutePythonCommandPath() {
+  return FilePath(FILE_PATH_LITERAL("python"));
+}
+
 bool TestServer::LaunchPython(const FilePath& testserver_path) {
-  CommandLine python_command(FilePath(FILE_PATH_LITERAL("python")));
+  CommandLine python_command(GetAbsolutePythonCommandPath());
   python_command.AppendArgPath(testserver_path);
   if (!AddCommandLineArguments(&python_command))
     return false;