Add --headless flag to Windows

headless/public/headless_shell.h

Index: headless/public/headless_shell.h
diff --git a/headless/public/headless_shell.h b/headless/public/headless_shell.h
index 0fd9066a80d5ef01842a9decea1c10e04b67503c..00cdca975a29fce8a9170a8d1203c64a9f9cc537 100644
--- a/headless/public/headless_shell.h
+++ b/headless/public/headless_shell.h
@@ -5,13 +5,20 @@
 #ifndef HEADLESS_PUBLIC_HEADLESS_SHELL_H_
 #define HEADLESS_PUBLIC_HEADLESS_SHELL_H_
 
-#include "headless/public/headless_export.h"
+#if defined(OS_WIN)
+#include "sandbox/win/src/sandbox_types.h"
+#endif
 
 namespace headless {
 
 // Start the Headless Shell application. Intended to be called early in main().
 // Returns the exit code for the process.
-HEADLESS_EXPORT int HeadlessShellMain(int argc, const char** argv);
+#if defined(OS_WIN)
+int HeadlessShellMain(HINSTANCE instance,
+                      sandbox::SandboxInterfaceInfo* sandbox_info);
+#else
+int HeadlessShellMain(int argc, const char** argv);
+#endif  // defined(OS_WIN)
 }  // namespace headless
 
 #endif  // HEADLESS_PUBLIC_HEADLESS_SHELL_H_