https://codereview.chromium.org/1026833004/diff/20001/chrome/common/BUILD.gn?context=25&column_width=80&tab_spaces=8 added the app_mode_app_support static_library() target. On non-Mac, all sources are filtered out.

On Windows, lib.exe silently and successfully does nothing when run with no inputs. So app_mode_app_support.lib never is written and the edge stays dirty always.

Maybe the best fix is to make that target a source_set.

(see also https://llvm.org/bugs/show_bug.cgi?id=27335)

My gn args are just `is_component_build=true`, and I build with `ninja -C out\gn app_mode_app_support`.