Reland: Take 2: Force python test server output to be unbuffered, so it doesn't mix with gtest outpu

net/test/local_test_server_win.cc

Index: net/test/local_test_server_win.cc
diff --git a/net/test/local_test_server_win.cc b/net/test/local_test_server_win.cc
index 0b3031239a127a847cb80349e13fb24fa2589293..3f3f0a560b79445335e1b708551f8d6422626ec7 100644
--- a/net/test/local_test_server_win.cc
+++ b/net/test/local_test_server_win.cc
@@ -94,6 +94,11 @@ bool LocalTestServer::LaunchPython(const FilePath& testserver_path) {
       .Append(FILE_PATH_LITERAL("python.exe"));
 
   CommandLine python_command(python_exe);
+
+  // Use unbuffered output, so that testserver output doesn't mix with gtest
+  // output in test log files. See http://crbug.com/147368.
+  python_command.AppendArg("-u");
+
   python_command.AppendArgPath(testserver_path);
   if (!AddCommandLineArguments(&python_command))
     return false;