headless: Librarify Headless Shell

headless/app/headless_shell_main.cc

Index: headless/app/headless_shell_main.cc
diff --git a/chrome/installer/mac/app/main.m b/headless/app/headless_shell_main.cc
similarity index 55%
copy from chrome/installer/mac/app/main.m
copy to headless/app/headless_shell_main.cc
index 33d21bf5719812ce0e609082979e88918375ba98..3ae4553b06854f9745690e4cc992267a7e4862ad 100644
--- a/chrome/installer/mac/app/main.m
+++ b/headless/app/headless_shell_main.cc
@@ -2,8 +2,8 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
-#import <AppKit/AppKit.h>
+#include "headless/public/headless_shell.h"
 
-int main(int argc, const char* argv[]) {
-  return NSApplicationMain(argc, argv);
+int main(int argc, const char** argv) {
+  return headless::HeadlessShellMain(argc, argv);
 }