Add always-on-top property to app windows

ui/views/widget/widget.cc

Index: ui/views/widget/widget.cc
diff --git a/ui/views/widget/widget.cc b/ui/views/widget/widget.cc
index 9261c7227d5f448a5f5083338c3b471e94275ff3..eea9c7e8677394c7073be86fcf9d65f713a2c7c1 100644
--- a/ui/views/widget/widget.cc
+++ b/ui/views/widget/widget.cc
@@ -181,7 +181,8 @@ Widget::Widget()
       last_mouse_event_was_move_(false),
       auto_release_capture_(true),
       root_layers_dirty_(false),
-      movement_disabled_(false) {
+      movement_disabled_(false),
+      is_always_on_top_(false) {
 }
 
 Widget::~Widget() {
@@ -398,6 +399,7 @@ void Widget::Init(const InitParams& in_params) {
     SetContentsView(params.delegate->GetContentsView());
     SetInitialBoundsForFramelessWindow(params.bounds);
   }
+  is_always_on_top_ = native_widget_->IsAlwaysOnTop();
   native_widget_initialized_ = true;
 }
 
@@ -656,6 +658,11 @@ void Widget::DisableInactiveRendering() {
 
 void Widget::SetAlwaysOnTop(bool on_top) {
   native_widget_->SetAlwaysOnTop(on_top);
+  is_always_on_top_ = native_widget_->IsAlwaysOnTop();
+}
+
+bool Widget::IsAlwaysOnTop() const {
+  return is_always_on_top_;
 }
 
 void Widget::Maximize() {