fix: remove skip-taskbar feature on Linux. (#35156)

* fix: remove skip-taskbar feature on Linux.

Marked as unsupported in e19, now removed in e20.

See #33226 for more information

* docs: remove skipTaskbar note in browserWindow

Co-authored-by: Charles Kerr <[email protected]>
Co-authored-by: Keeley Hammond <[email protected]>

docs/api/browser-window.md

@@ -1323,7 +1323,7 @@ win.setSheetOffset(toolbarRect.height)
 
 Starts or stops flashing the window to attract user's attention.
 
-#### `win.setSkipTaskbar(skip)`
+#### `win.setSkipTaskbar(skip)` _macOS_ _Windows_
 
 * `skip` boolean
 

shell/browser/native_window_views.cc

@@ -303,14 +303,9 @@ NativeWindowViews::NativeWindowViews(const gin_helper::Dictionary& options,
 
 #if defined(USE_OZONE_PLATFORM_X11)
   if (IsX11()) {
-    // TODO(ckerr): remove in Electron v20.0.0
     // Before the window is mapped the SetWMSpecState can not work, so we have
     // to manually set the _NET_WM_STATE.
     std::vector<x11::Atom> state_atom_list;
-    bool skip_taskbar = false;
-    if (options.Get(options::kSkipTaskbar, &skip_taskbar) && skip_taskbar) {
-      state_atom_list.push_back(x11::GetAtom("_NET_WM_STATE_SKIP_TASKBAR"));
-    }
 
     // Before the window is mapped, there is no SHOW_FULLSCREEN_STATE.
     if (fullscreen) {