mash: Convert StatusAreaWidgetDelegate to wm common types

ash/common/shelf/wm_shelf.h

Index: ash/common/shelf/wm_shelf.h
diff --git a/ash/common/shelf/wm_shelf.h b/ash/common/shelf/wm_shelf.h
index 198f9cf27f5b42f0a182b5893db2cb5f97b503f8..1e7ab27bfebb3bbdcbcbe3e6c12fa65252a91c53 100644
--- a/ash/common/shelf/wm_shelf.h
+++ b/ash/common/shelf/wm_shelf.h
@@ -64,6 +64,13 @@ class ASH_EXPORT WmShelf {
   // no item for the specified window an empty rect is returned.
   virtual gfx::Rect GetScreenBoundsOfItemIconForWindow(WmWindow* window) = 0;
 
+  // Handles a gesture |event| coming from a |target_window| outside the shelf
+  // (e.g. the status area widget). Allows support for behaviors like toggling
+  // auto-hide with an edge swipe, even if that gesture event hits another
+  // window. Returns true if the event was handled.
+  virtual bool ProcessGestureEvent(const ui::GestureEvent& event,
+                                   WmWindow* target_window) = 0;
+
   // TODO(jamescook): Nuke when ash_sysui is removed. http://crbug.com/621112
   virtual void UpdateAutoHideForMouseEvent(ui::MouseEvent* event) = 0;
   virtual void UpdateAutoHideForGestureEvent(ui::GestureEvent* event) = 0;