[BUG] headless_shell_switches.cc missing when build nw in branch nw83

[dyk98]

when I run ninja -C out/nw nwjs in branch nw83, it throw error like
ninja: error: '../../headless/app/headless_shell_switches.cc', needed by 'obj/headless/headless_shell_lib/headless_shell_switches.o', missing and no known rule to make it
I found the headless_shell_switches.cc was deleted in branch nw73

[dyk98]

I fix this issue by delete

if ((is_linux || is_mac) && is_component_build) {
    sources += [
      "app/headless_shell_switches.cc",
      "app/headless_shell_switches.h",
    ]
  }

in src/headless/BUILD.gn