Support detaching/attaching panels via inter-strip drags.

chrome/browser/ui/panels/panel.cc

Index: chrome/browser/ui/panels/panel.cc
diff --git a/chrome/browser/ui/panels/panel.cc b/chrome/browser/ui/panels/panel.cc
index 8e08f364448f60eccb174968c11a378eb89bc606..155965b91fc37955f9e8dd761098feb723658790 100644
--- a/chrome/browser/ui/panels/panel.cc
+++ b/chrome/browser/ui/panels/panel.cc
@@ -50,8 +50,7 @@ Panel::Panel(Browser* browser, const gfx::Size& requested_size)
       restored_size_(requested_size),
       auto_resizable_(false),
       expansion_state_(EXPANDED),
-      old_expansion_state_(EXPANDED),
-      app_icon_visible_(true) {
+      old_expansion_state_(EXPANDED) {
 }
 
 Panel::~Panel() {
@@ -143,12 +142,13 @@ void Panel::SetSizeRange(const gfx::Size& min_size, const gfx::Size& max_size) {
 }
 
 void Panel::SetAppIconVisibility(bool visible) {
-  if (app_icon_visible_ == visible)
-    return;
-  app_icon_visible_ = visible;
   native_panel_->SetPanelAppIconVisibility(visible);
 }
 
+void Panel::SetAlwaysOnTop(bool on_top) {
+  native_panel_->SetPanelAlwaysOnTop(on_top);
+}
+
 void Panel::MoveToStrip(PanelStrip* new_strip) {
   DCHECK_NE(panel_strip_, new_strip);
   if (panel_strip_)