[Refactor] Cache the views::Widget* that the FrameMaximizeButton acts on

ash/wm/caption_buttons/frame_maximize_button.h

 // Copyright 2013 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_CAPTION_BUTTONS_FRAME_MAXIMIZE_BUTTON_H_
 #define ASH_WM_CAPTION_BUTTONS_FRAME_MAXIMIZE_BUTTON_H_
 
 #include "ash/ash_export.h"
 #include "ash/wm/caption_buttons/maximize_bubble_frame_state.h"
 #include "ash/wm/workspace/snap_types.h"
 #include "base/memory/scoped_ptr.h"
 #include "base/timer/timer.h"
 #include "ui/aura/window_observer.h"
 #include "ui/views/controls/button/image_button.h"
 #include "ui/views/widget/widget_observer.h"
 
 namespace views {
-class NonClientFrameView;
+class Widget;
 }
 
 namespace ash {
 
 namespace internal {
 class PhantomWindowController;
 class SnapSizer;
 }
 
 class MaximizeBubbleController;
 
 // Button used for the maximize control on the frame. Handles snapping logic.
 class ASH_EXPORT FrameMaximizeButton : public views::ImageButton,
                                        public views::WidgetObserver,
                                        public aura::WindowObserver {
  public:
   FrameMaximizeButton(views::ButtonListener* listener,
-                      views::NonClientFrameView* frame);
+                      views::Widget* frame);
   virtual ~FrameMaximizeButton();
 
   // Updates |snap_type_| based on a a given snap type. This is used by
   // external hover events from the button menu.
   void SnapButtonHovered(SnapType type);
 
   // The user clicked the |type| button and the action needs to be performed,
   // which will at the same time close the window.
   void ExecuteSnapAndCloseMenu(SnapType type);
 
@@ skipping 84 matching lines @@
   // Converts location to screen coordinates and returns it. These are the
   // coordinates used by the SnapSizer.
   gfx::Point LocationForSnapSizer(const gfx::Point& location) const;
 
   // Snaps the window to the current snap position.
   void Snap(const internal::SnapSizer& snap_sizer);
 
   // Determine the maximize type of this window.
   MaximizeBubbleFrameState GetMaximizeBubbleFrameState() const;
 
-  // Frame that the maximize button acts on.
-  views::NonClientFrameView* frame_;
+  // Widget that the maximize button acts on. This is different than the widget
+  // which contains the button in the case of AppNonClientFrameViewAsh.
+  views::Widget* frame_;
+
+  // True if we have put observers on |frame_|.
+  bool observing_frame_;
 
   // Renders the snap position.
   scoped_ptr<internal::PhantomWindowController> phantom_window_;
 
   // Is snapping enabled? Set on press so that in drag we know whether we
   // should show the snap locations.
   bool is_snap_enabled_;
 
   // Did the user drag far enough to trigger snapping?
   bool exceeded_drag_threshold_;
 
-  // Remember the widget on which we have put some an observers,
-  // so that we can remove it upon destruction.
-  views::Widget* widget_;
-
   // Location of the press.
   gfx::Point press_location_;
 
   // True if the press was triggered by a gesture/touch.
   bool press_is_gesture_;
 
   // Current snap type.
   SnapType snap_type_;
 
   scoped_ptr<internal::SnapSizer> snap_sizer_;
 
   scoped_ptr<EscapeEventFilter> escape_event_filter_;
 
   base::OneShotTimer<FrameMaximizeButton> update_timer_;
 
   scoped_ptr<MaximizeBubbleController> maximizer_;
 
   // The delay of the bubble appearance.
   int bubble_appearance_delay_ms_;
 
   DISALLOW_COPY_AND_ASSIGN(FrameMaximizeButton);
 };
 
 }  // namespace ash
 
 #endif  // ASH_WM_CAPTION_BUTTONS_FRAME_MAXIMIZE_BUTTON_H_