Use Ash's ShelfWindowWatcher for app panel windows.

ash/aura/wm_window_aura.cc

Index: ash/aura/wm_window_aura.cc
diff --git a/ash/aura/wm_window_aura.cc b/ash/aura/wm_window_aura.cc
index f43120accd6dc502a3cb412b27d7e8b8e2f604cd..209466a323775f75af2bada786646b93772496b6 100644
--- a/ash/aura/wm_window_aura.cc
+++ b/ash/aura/wm_window_aura.cc
@@ -367,6 +367,16 @@ void WmWindowAura::SetIntProperty(WmWindowProperty key, int value) {
   NOTREACHED();
 }
 
+gfx::ImageSkia WmWindowAura::GetWindowIcon() {
+  gfx::ImageSkia* image = window_->GetProperty(aura::client::kWindowIconKey);
+  return image ? *image : gfx::ImageSkia();
+}
+
+gfx::ImageSkia WmWindowAura::GetAppIcon() {
+  gfx::ImageSkia* image = window_->GetProperty(aura::client::kAppIconKey);
+  return image ? *image : gfx::ImageSkia();
+}
+
 const wm::WindowState* WmWindowAura::GetWindowState() const {
   return ash::wm::GetWindowState(window_);
 }
@@ -839,6 +849,8 @@ void WmWindowAura::OnWindowPropertyChanged(aura::Window* window,
   WmWindowProperty wm_property;
   if (key == aura::client::kAlwaysOnTopKey) {
     wm_property = WmWindowProperty::ALWAYS_ON_TOP;
+  } else if (key == aura::client::kAppIconKey) {
+    wm_property = WmWindowProperty::APP_ICON;
   } else if (key == aura::client::kExcludeFromMruKey) {
     wm_property = WmWindowProperty::EXCLUDE_FROM_MRU;
   } else if (key == aura::client::kModalKey) {
@@ -853,6 +865,8 @@ void WmWindowAura::OnWindowPropertyChanged(aura::Window* window,
     wm_property = WmWindowProperty::SNAP_CHILDREN_TO_PIXEL_BOUNDARY;
   } else if (key == aura::client::kTopViewInset) {
     wm_property = WmWindowProperty::TOP_VIEW_INSET;
+  } else if (key == aura::client::kWindowIconKey) {
+    wm_property = WmWindowProperty::WINDOW_ICON;
   } else {
     return;
   }