Add always-on-top property to app windows

ui/views/widget/desktop_aura/desktop_root_window_host_x11.cc

Index: ui/views/widget/desktop_aura/desktop_root_window_host_x11.cc
diff --git a/ui/views/widget/desktop_aura/desktop_root_window_host_x11.cc b/ui/views/widget/desktop_aura/desktop_root_window_host_x11.cc
index d09dc09385c0ac2c83ed0550695eb1fb03ea0db6..3c9aa171e835653e22e5af26e481df4ef76a54ee 100644
--- a/ui/views/widget/desktop_aura/desktop_root_window_host_x11.cc
+++ b/ui/views/widget/desktop_aura/desktop_root_window_host_x11.cc
@@ -124,6 +124,7 @@ DesktopRootWindowHostX11::DesktopRootWindowHostX11(
       window_mapped_(false),
       focus_when_shown_(false),
       is_fullscreen_(false),
+      always_on_top_(false),
       current_cursor_(ui::kCursorNull),
       native_widget_delegate_(native_widget_delegate),
       desktop_native_widget_aura_(desktop_native_widget_aura) {
@@ -432,11 +433,16 @@ bool DesktopRootWindowHostX11::HasCapture() const {
 }
 
 void DesktopRootWindowHostX11::SetAlwaysOnTop(bool always_on_top) {
+  always_on_top_ = always_on_top;
   SetWMSpecState(always_on_top,
                  atom_cache_.GetAtom("_NET_WM_STATE_ABOVE"),
                  None);
 }
 
+bool DesktopRootWindowHostX11::IsAlwaysOnTop() const {
+  return always_on_top_;
+}
+
 void DesktopRootWindowHostX11::SetWindowTitle(const string16& title) {
   XStoreName(xdisplay_, xwindow_, UTF16ToUTF8(title).c_str());
 }
@@ -914,6 +920,20 @@ void DesktopRootWindowHostX11::InitX11Window(
                      reinterpret_cast<unsigned char*>(&atom), 1);
   }
 
+  // If the window should stay on top of other windows, add the
+  // _NET_WM_STATE_ABOVE property.
+  always_on_top_ = params.keep_on_top;
+  if (always_on_top_) {
+    Atom atom = atom_cache_.GetAtom("_NET_WM_STATE_ABOVE");
+    XChangeProperty (xdisplay_,

[Elliot Glaysher, 2013/10/08 18:05:00]

This will clobber the XChangeProperty immediately above. _NET_WM_STATE takes an
array, and you're possibly overwriting the previous one length array. We have a
nice utility function, ui::SetAtomArrayProperty, in x11_util.h which can handle
that.

Documentation:
http://standards.freedesktop.org/wm-spec/wm-spec-1.3.html#id2731936

[tmdiep, 2013/10/09 02:15:04]

Thanks for that. Fixed.

+                     xwindow_,
+                     atom_cache_.GetAtom("_NET_WM_STATE"),
+                     XA_ATOM,
+                     32,
+                     PropModeAppend,
+                     reinterpret_cast<unsigned char*>(&atom), 1);
+  }
+
   if (!params.wm_class_name.empty() || !params.wm_class_class.empty()) {
     ui::SetWindowClassHint(
         xdisplay_, xwindow_, params.wm_class_name, params.wm_class_class);
@@ -1356,6 +1376,7 @@ bool DesktopRootWindowHostX11::Dispatch(const base::NativeEvent& event) {
         }
 
         is_fullscreen_ = HasWMSpecProperty("_NET_WM_STATE_FULLSCREEN");
+        always_on_top_ = HasWMSpecProperty("_NET_WM_STATE_ABOVE");
 
         // Now that we have different window properties, we may need to
         // relayout the window. (The windows code doesn't need this because