Add --headless flag to Windows

chrome/app/chrome_main.cc

Index: chrome/app/chrome_main.cc
diff --git a/chrome/app/chrome_main.cc b/chrome/app/chrome_main.cc
index 0d7a8ad573e4f220d0fff90b8afe7255dba4b18f..7481030f4cfa0f3c958ee858c804bb54e7f9b6a6 100644
--- a/chrome/app/chrome_main.cc
+++ b/chrome/app/chrome_main.cc
@@ -93,18 +93,24 @@ int ChromeMain(int argc, const char** argv) {
 
 #if !defined(OS_WIN)
   base::CommandLine::Init(params.argc, params.argv);
+#else
+  base::CommandLine::Init(0, NULL);

[sky, 2017/03/22 16:05:03]

Why do you have to add this? Aren't we already init'ing the command line?
Assuming you need this, NULL -> nullptr and move this to be between 88/89 and
line 95 to between 91/92.

[dvallet, 2017/03/27 05:59:50]

Done. You are right, it's not needed.
I've moved the initialization of Linux to 91/92 

+#endif
   const base::CommandLine* command_line(base::CommandLine::ForCurrentProcess());
   ALLOW_UNUSED_LOCAL(command_line);
-#endif
 
-#if defined(OS_LINUX) || defined(OS_MACOSX)
+#if defined(OS_LINUX) || defined(OS_MACOSX) || defined(OS_WIN)
   if (command_line->HasSwitch(switches::kHeadless)) {
 #if defined(OS_MACOSX)
     SetUpBundleOverrides();
 #endif
+#if defined(OS_WIN)
+    return headless::HeadlessShellMain(instance, sandbox_info);
+#else
     return headless::HeadlessShellMain(argc, argv);

[sky, 2017/03/22 16:05:03]

Can HeadlessShellMain take ContentMainParams so that you don't need all the
ifdefs here?

[Sami, 2017/03/22 19:46:25]

We could add an override for that, but for users who embed the library we should
also keep the old entrypoint for compatibility.

[dvallet, 2017/03/27 05:59:50]

Done

+#endif
   }
-#endif  // defined(OS_LINUX) || defined(OS_MACOSX)
+#endif  // defined(OS_LINUX) || defined(OS_MACOSX) || defined(OS_WIN)
 
 #if BUILDFLAG(ENABLE_PACKAGE_MASH_SERVICES)
   version_info::Channel channel = chrome::GetChannel();