Add --headless flag to Windows

headless/public/headless_browser.h

Index: headless/public/headless_browser.h
diff --git a/headless/public/headless_browser.h b/headless/public/headless_browser.h
index 4b18f565b9e8fc2f2b8cb91ad0bb885a26a8a64e..b6fdc3e272e6057186e1c11350d3d3c83bfe8c8e 100644
--- a/headless/public/headless_browser.h
+++ b/headless/public/headless_browser.h
@@ -22,6 +22,10 @@
 #include "net/base/ip_endpoint.h"
 #include "ui/gfx/geometry/size.h"
 
+#if defined(OS_WIN)
+#include "sandbox/win/src/sandbox_types.h"
+#endif
+
 namespace base {
 class MessagePump;
 class SingleThreadTaskRunner;
@@ -164,6 +168,14 @@ struct HeadlessBrowser::Options {
   bool enable_crash_reporter;
   base::FilePath crash_dumps_dir;
 
+#if defined(OS_WIN)
+  // Set hardware instance if available, otherwise it defaults to 0.
+  HINSTANCE instance;
+
+  // Set with sandboc information. This has to be already initialized.
+  sandbox::SandboxInterfaceInfo* sandbox_info;
+#endif
+
   // Reminder: when adding a new field here, do not forget to add it to
   // HeadlessBrowserContextOptions (where appropriate).
  private:
@@ -186,6 +198,10 @@ class HeadlessBrowser::Options::Builder {
   Builder& SetDisableSandbox(bool disable_sandbox);
   Builder& SetGLImplementation(const std::string& gl_implementation);
   Builder& AddMojoServiceName(const std::string& mojo_service_name);
+#if defined(OS_WIN)
+  Builder& SetInstance(HINSTANCE instance);
+  Builder& SetSandboxInfo(sandbox::SandboxInterfaceInfo* sandbox_info);
+#endif
 
   // Per-context settings.
 
@@ -229,7 +245,9 @@ class HeadlessBrowser::Options::Builder {
 //
 // [1]
 // https://chromium.googlesource.com/chromium/src/+/master/docs/linux_zygote.md
+#if !defined(OS_WIN)
 void RunChildProcessIfNeeded(int argc, const char** argv);
+#endif
 
 // Main entry point for running the headless browser. This function constructs
 // the headless browser instance, passing it to the given