mash: Convert FocusCycler to wm common types and move to //ash/common

ash/common/wm_window.h

 // Copyright 2016 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_COMMON_WM_WINDOW_H_
 #define ASH_COMMON_WM_WINDOW_H_
 
 #include <memory>
 #include <vector>
 
@@ skipping 13 matching lines @@
 class Point;
 class Rect;
 class Size;
 class Transform;
 }
 
 namespace ui {
 class Layer;
 }
 
+namespace views {
+class Widget;
+}
+
 namespace ash {
 
 class WmLayoutManager;
 class WmRootWindowController;
 class WmShell;
 class WmWindowObserver;
 enum class WmWindowProperty;
 
 namespace wm {
 class WMEvent;
@@ skipping 152 matching lines @@
   virtual void ReleaseCapture() = 0;
 
   virtual bool HasRestoreBounds() const = 0;
 
   virtual void SetAlwaysOnTop(bool value) = 0;
   virtual bool IsAlwaysOnTop() const = 0;
 
   virtual void Hide() = 0;
   virtual void Show() = 0;
 
+  // Returns the widget associated with this window, or null if not associated
+  // with a widget. Only ash system UI widgets are returned, not widgets created
+  // by the mus window manager code to show a non-client frame.
+  virtual views::Widget* GetWidget() = 0;

[msw, 2016/06/16 23:57:44]

Hmm, Scott may have some advice here; but I guess it seems okay to me.
(I wonder if it would be helpful to return the mus wm frame widget...)

[sky, 2016/06/17 00:08:29]

I'm ok with this, but I recommend a clearer name. WmWindowMus calls this type of
widget 'internal'. GetInternalWidget? If we need this to return either type,
then GetWidget() is fine.

[James Cook, 2016/06/17 03:39:29]

I only need the internal widget, so I went with GetInternalWidget().

+
   // Requests the window to close and destroy itself. This is intended to
   // forward to an associated widget.
   virtual void CloseWidget() = 0;
 
   virtual bool IsFocused() const = 0;
 
   virtual bool IsActive() const = 0;
   virtual void Activate() = 0;
   virtual void Deactivate() = 0;
 
@@ skipping 41 matching lines @@
   virtual void AddObserver(WmWindowObserver* observer) = 0;
   virtual void RemoveObserver(WmWindowObserver* observer) = 0;
 
  protected:
   virtual ~WmWindow() {}
 };
 
 }  // namespace ash
 
 #endif  // ASH_COMMON_WM_WINDOW_H_