Refactors DimWindow and moves to ash/common

ash/common/wm/window_dimmer.h

Index: ash/common/wm/window_dimmer.h
diff --git a/ash/wm/dim_window.h b/ash/common/wm/window_dimmer.h
similarity index 37%
rename from ash/wm/dim_window.h
rename to ash/common/wm/window_dimmer.h
index 8d86c63d02dbeba44449d2a25a40698ce950a786..e20f9340809a3559db5190eae4c092c1751a7785 100644
--- a/ash/wm/dim_window.h
+++ b/ash/common/wm/window_dimmer.h
@@ -2,34 +2,49 @@
 // Use of this source code is governed by a BSD-style license that can be
 // found in the LICENSE file.
 
+#ifndef ASH_COMMON_WINDOW_DIMMER_H_

[James Cook, 2016/09/09 00:03:35]

Aside: I find it amusing how often we (I) forget header guards.

+#define ASH_COMMON_WINDOW_DIMMER_H_
+
 #include "ash/ash_export.h"
+#include "ash/common/wm_window_observer.h"
 #include "base/macros.h"
-#include "ui/aura/window.h"
-#include "ui/aura/window_observer.h"
 
 namespace ash {
 
-// A window used to dim the child windows of the given container.
-class ASH_EXPORT DimWindow : public aura::Window, public aura::WindowObserver {
+// WindowDimmer creates a window that is used to dim siblings of window.

[James Cook, 2016/09/09 00:03:35]

nit: of a window

[sky, 2016/09/09 03:50:04]

Done.

+// WindowDimmer, and the window it creates, are owned by the parent window of
+// the WindowDimmer. You can trigger deletion explicitly by calling Destroy().
+class ASH_EXPORT WindowDimmer : public WmWindowObserver {
  public:
   // Return a dim window for the container if any, or nullptr.
-  static DimWindow* Get(aura::Window* container);
+  static WindowDimmer* Get(WmWindow* container);
+
+  explicit WindowDimmer(WmWindow* parent);
 
-  explicit DimWindow(aura::Window* parent);
-  ~DimWindow() override;
+  // Explicitly deletes a WindowDimmer.
+  void Destroy();
 
   void SetDimOpacity(float target_opacity);
 
-  // aura::WindowObserver:
-  void OnWindowBoundsChanged(aura::Window* window,
+  WmWindow* parent() { return parent_; }
+  WmWindow* window() { return window_; }
+
+  // WmWindowObserver:
+  void OnWindowBoundsChanged(WmWindow* window,
                              const gfx::Rect& old_bounds,
                              const gfx::Rect& new_bounds) override;
-  void OnWindowDestroying(aura::Window* window) override;
 
  private:
-  aura::Window* parent_;
+  struct Data;
 
-  DISALLOW_COPY_AND_ASSIGN(DimWindow);
+  ~WindowDimmer() override;
+
+  WmWindow* parent_;
+  WmWindow* window_;
+
+  DISALLOW_COPY_AND_ASSIGN(WindowDimmer);
 };
 
 }  // namespace ash
+
+#endif  // ASH_COMMON_WINDOW_DIMMER_H_