Eliminate Shell::RootWindowList in favor of aura::Window::Windows.

ash/wm/partial_screenshot_view.h

Index: ash/wm/partial_screenshot_view.h
diff --git a/ash/wm/partial_screenshot_view.h b/ash/wm/partial_screenshot_view.h
index 85b9f81f28bbdbe42582d4a1634b0c34e147072b..8d799e3132b428fbcd49107994e5cc1aa2c01520 100644
--- a/ash/wm/partial_screenshot_view.h
+++ b/ash/wm/partial_screenshot_view.h
@@ -13,10 +13,6 @@
 #include "ui/gfx/point.h"
 #include "ui/views/widget/widget_delegate.h"
 
-namespace aura {
-class RootWindow;
-}
-
 namespace ash {
 class ScreenshotDelegate;
 
@@ -42,7 +38,7 @@ class ASH_EXPORT PartialScreenshotView : public views::WidgetDelegateView {
   virtual ~PartialScreenshotView();
 
   // Initializes partial screenshot UI widget for |root_window|.
-  void Init(aura::RootWindow* root_window);
+  void Init(aura::Window* root_window);
 
   // Returns the currently selected region.
   gfx::Rect GetScreenshotRect() const;