Polish launcher tooltip visibility (2nd try).

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"
 #include "ash/shell_observer.h"
 #include "ash/wm/shelf_types.h"
 #include "base/basictypes.h"
 #include "base/compiler_specific.h"
+#include "base/observer_list.h"
 #include "base/timer.h"
 #include "ui/aura/client/activation_change_observer.h"
 #include "ui/aura/layout_manager.h"
 #include "ui/gfx/insets.h"
 #include "ui/gfx/rect.h"
 
 namespace aura {
 class RootWindow;
 }
 
@@ skipping 27 matching lines @@
 
     // Nothing is shown. Used for fullscreen windows.
     HIDDEN,
   };
 
   enum AutoHideState {
     AUTO_HIDE_SHOWN,
     AUTO_HIDE_HIDDEN,
   };
 
+  class ASH_EXPORT Observer {
+   public:
+    // Called when the visibility change is scheduled.
+    virtual void WillVisibilityStateChange(VisibilityState new_state) {}
+
+    // Called when the auto hide state is changed.
+    virtual void OnAutoHideStateChanged(AutoHideState new_state) {}
+  };
+
   // We reserve a small area at the bottom of the workspace area to ensure that
   // the bottom-of-window resize handle can be hit.
   // TODO(jamescook): Some day we may want the workspace area to be an even
   // multiple of the size of the grid (currently 8 pixels), which will require
   // removing this and finding a way for hover and click events to pass through
   // the invisible parts of the launcher.
   static const int kWorkspaceAreaBottomInset;
 
   // Size of the shelf when auto-hidden.
   static const int kAutoHideSize;
@@ skipping 51 matching lines @@
   // Invoked by the shelf/launcher when the auto-hide state may have changed.
   void UpdateAutoHideState();
 
   VisibilityState visibility_state() const { return state_.visibility_state; }
   AutoHideState auto_hide_state() const { return state_.auto_hide_state; }
 
   // Sets whether any windows overlap the shelf. If a window overlaps the shelf
   // the shelf renders slightly differently.
   void SetWindowOverlapsShelf(bool value);
 
+  void AddObserver(Observer* observer);
+  void RemoveObserver(Observer* observer);
+
   // Overridden from aura::LayoutManager:
   virtual void OnWindowResized() OVERRIDE;
   virtual void OnWindowAddedToLayout(aura::Window* child) OVERRIDE;
   virtual void OnWillRemoveWindowFromLayout(aura::Window* child) OVERRIDE;
   virtual void OnWindowRemovedFromLayout(aura::Window* child) OVERRIDE;
   virtual void OnChildWindowVisibilityChanged(aura::Window* child,
                                               bool visible) OVERRIDE;
   virtual void SetChildBounds(aura::Window* child,
                               const gfx::Rect& requested_bounds) OVERRIDE;
 
@@ skipping 102 matching lines @@
 
   // Do any windows overlap the shelf? This is maintained by WorkspaceManager.
   bool window_overlaps_shelf_;
 
   base::OneShotTimer<ShelfLayoutManager> auto_hide_timer_;
 
   // EventFilter used to detect when user moves the mouse over the launcher to
   // trigger showing the launcher.
   scoped_ptr<AutoHideEventFilter> event_filter_;
 
+  ObserverList<Observer> observers_;
+
   DISALLOW_COPY_AND_ASSIGN(ShelfLayoutManager);
 };
 
 }  // namespace internal
 }  // namespace ash
 
 #endif  // ASH_WM_SHELF_LAYOUT_MANAGER_H_