Add --headless flag to Windows

headless/app/headless_shell.cc

Index: headless/app/headless_shell.cc
diff --git a/headless/app/headless_shell.cc b/headless/app/headless_shell.cc
index d6d6adeb758a5ef06ce2821d3973911297b22c74..d91fea3bdfa15aca2983371a047844c0fba10b07 100644
--- a/headless/app/headless_shell.cc
+++ b/headless/app/headless_shell.cc
@@ -5,6 +5,7 @@
 #include <memory>
 #include <sstream>
 #include <string>
+#include <utility>
 
 #include "base/base64.h"
 #include "base/base_switches.h"
@@ -26,6 +27,10 @@
 #include "net/base/net_errors.h"
 #include "ui/gfx/geometry/size.h"
 
+#if defined(OS_WIN)
+#include "sandbox/win/src/sandbox_types.h"
+#endif
+
 namespace headless {
 namespace {
 // Address where to listen to incoming DevTools connections.
@@ -430,11 +435,20 @@ bool ValidateCommandLine(const base::CommandLine& command_line) {
   return true;
 }
 
+#if defined(OS_WIN)
+int HeadlessShellMain(HINSTANCE instance,
+                      sandbox::SandboxInterfaceInfo* sandbox_info) {
+  base::CommandLine::Init(0, NULL);
+  HeadlessBrowser::Options::Builder builder(0, NULL);
+  builder.SetInstance(instance);
+  builder.SetSandboxInfo(std::move(sandbox_info));
+#else
 int HeadlessShellMain(int argc, const char** argv) {
   base::CommandLine::Init(argc, argv);
   RunChildProcessIfNeeded(argc, argv);
-  HeadlessShell shell;
   HeadlessBrowser::Options::Builder builder(argc, argv);
+#endif  // defined(OS_WIN)
+  HeadlessShell shell;
 
   // Enable devtools if requested.
   const base::CommandLine& command_line(