ash: Do not show the arrow in the tray bubbles when the tray isn't visible.

ash/wm/shelf_layout_manager.h

 // Copyright (c) 2012 The Chromium Authors. All rights reserved.
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
 #ifndef ASH_WM_SHELF_LAYOUT_MANAGER_H_
 #define ASH_WM_SHELF_LAYOUT_MANAGER_H_
 #pragma once
 
 #include "ash/ash_export.h"
 #include "ash/launcher/launcher.h"
@@ skipping 69 matching lines @@
   const views::Widget* launcher_widget() const {
     return launcher_ ? launcher_->widget() : NULL;
   }
   views::Widget* status() { return status_; }
 
   bool in_layout() const { return in_layout_; }
 
   // See description above field.
   int shelf_height() const { return shelf_height_; }
 
+  // Returns whether the shelf and its contents (launcher, status) are visible
+  // on the screen.
+  bool IsVisible() const;
+
   // Returns the bounds the specified window should be when maximized.
   gfx::Rect GetMaximizedWindowBounds(aura::Window* window) const;
   gfx::Rect GetUnmaximizedWorkAreaBounds(aura::Window* window) const;
 
   // The launcher is typically created after the layout manager.
   void SetLauncher(Launcher* launcher);
 
   // Stops any animations and sets the bounds of the launcher and status
   // widgets.
   void LayoutShelf();
@@ skipping 102 matching lines @@
   // trigger showing the launcher.
   scoped_ptr<AutoHideEventFilter> event_filter_;
 
   DISALLOW_COPY_AND_ASSIGN(ShelfLayoutManager);
 };
 
 }  // namespace internal
 }  // namespace ash
 
 #endif  // ASH_WM_SHELF_LAYOUT_MANAGER_H_