Make the windows_version.h functions threadsafe by using a singleton.

chrome/test/out_of_proc_test_runner.cc

Index: chrome/test/out_of_proc_test_runner.cc
===================================================================
--- chrome/test/out_of_proc_test_runner.cc	(revision 80667)
+++ chrome/test/out_of_proc_test_runner.cc	(working copy)
@@ -579,6 +579,18 @@
     return ChromeTestSuite(argc, argv).Run();
   }
 
+  // The exit manager is in charge of calling the dtors of singleton objects.
+  // On Windows, the call to ChromeMain() below will construct one for the
+  // chrome.dll module, but that global is not shared with this module, so if
+  // chrome.dll calls back out to this module and the called code uses a
+  // singleton, we'll need this.  On other platforms, ChromeMain() isn't called
+  // at all below, so this is the lone exit manager for any code after this
+  // point.
+  // NOTE: We can't init this atop main() because ChromeTestSuite, as a subclass
+  // of TestSuite, creates one.  So we wait until after the Run() call above to
+  // create the manager for the code path that _doesn't_ use ChromeTestSuite.
+  base::AtExitManager exit_manager;
+
 #if defined(OS_WIN)
   if (command_line->HasSwitch(switches::kProcessType)) {
     // This is a child process, call ChromeMain.