mash: Convert StatusAreaWidgetDelegate to wm common types

ash/aura/wm_shelf_aura.cc

Index: ash/aura/wm_shelf_aura.cc
diff --git a/ash/aura/wm_shelf_aura.cc b/ash/aura/wm_shelf_aura.cc
index c6f2a80c069968d77719c043ccc587fb5ff6df23..bacc3f2fe9f293a6ac7b8bdfad7cccc83a465786 100644
--- a/ash/aura/wm_shelf_aura.cc
+++ b/ash/aura/wm_shelf_aura.cc
@@ -123,6 +123,12 @@ gfx::Rect WmShelfAura::GetScreenBoundsOfItemIconForWindow(WmWindow* window) {
       WmWindowAura::GetAuraWindow(window));
 }
 
+bool WmShelfAura::ProcessGestureEvent(const ui::GestureEvent& event,
+                                      WmWindow* target_window) {
+  return gesture_handler_.ProcessGestureEvent(
+      event, WmWindowAura::GetAuraWindow(target_window));
+}
+
 void WmShelfAura::UpdateAutoHideForMouseEvent(ui::MouseEvent* event) {
   // Auto-hide support for ash_sysui.
   if (Shell::GetInstance()->in_mus() && shelf_layout_manager_)