Allow the user to drag a window from one display to another

ash/wm/workspace/workspace_window_resizer.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_WORKSPACE_WINDOW_RESIZER_H_
 #define ASH_WM_WORKSPACE_WINDOW_RESIZER_H_
 
 #include <vector>
 
 #include "ash/wm/window_resizer.h"
 #include "base/compiler_specific.h"
 #include "base/memory/scoped_ptr.h"
 
+namespace aura {
+class RootWindow;
+}  // namespace aura
+
 namespace ash {
 namespace internal {
 
 class PhantomWindowController;
 class SnapSizer;
 
 // WindowResizer implementation for workspaces. This enforces that windows are
 // not allowed to vertically move or resize outside of the work area. As windows
 // are moved outside the work area they are shrunk. We remember the height of
 // the window before it was moved so that if the window is again moved up we
@@ skipping 74 matching lines @@
       int grid_size) const;
 
   // Returns true if the window touches the bottom edge of the work area.
   bool TouchesBottomOfScreen() const;
 
   // Returns a coordinate along the primary axis. Used to share code for
   // left/right multi window resize and top/bottom resize.
   int PrimaryAxisSize(const gfx::Size& size) const;
   int PrimaryAxisCoordinate(int x, int y) const;
 
-  // Updates the bounds of the phantom window.
+  // Updates the bounds of the phantom window for window snapping.
   void UpdatePhantomWindow(
       const gfx::Point& location,
       const gfx::Rect& bounds,
       int grid_size);
 
+  // Updates the bounds of the phantom window for window dragging.
+  void UpdateDragPhantomWindow(aura::RootWindow* another_root,
+                               const gfx::Rect& window_bounds_in_screen);
+
   // Restacks the windows z-order position so that one of the windows is at the
   // top of the z-order, and the rest directly underneath it.
   void RestackWindows();
 
   // Returns the SnapType for the specified point. SNAP_NONE is used if no
   // snapping should be used.
   SnapType GetSnapType(const gfx::Point& location) const;
 
   // Returns true if we should allow the mouse pointer to warp.
   bool ShouldAllowMouseWarp() const;
@@ skipping 28 matching lines @@
   // Sum of sizes in |min_size_|.
   int total_min_;
 
   // Sum of the sizes in |initial_size_|.
   int total_initial_size_;
 
   // Gives a previews of where the the window will end up. Only used if there
   // is a grid and the caption is being dragged.
   scoped_ptr<PhantomWindowController> phantom_window_controller_;
 
+  // For now, we show a phantom window on the other root window during dragging.
+  // TODO(yusukes): Show a semi-transparent image (screen shot) of the window
+  // instead.
+  scoped_ptr<PhantomWindowController> drag_phantom_window_controller_;
+
   // Used to determine the target position of a snap.
   scoped_ptr<SnapSizer> snap_sizer_;
 
   // Last SnapType.
   SnapType snap_type_;
 
   // Number of mouse moves since the last bounds change. Only used for phantom
   // placement to track when the mouse is moved while pushed against the edge of
   // the screen.
   int num_mouse_moves_since_bounds_change_;
 
   DISALLOW_COPY_AND_ASSIGN(WorkspaceWindowResizer);
 };
 
 }  // namespace internal
 }  // namespace ash
 
 #endif  // ASH_WM_WORKSPACE_WINDOW_RESIZER_H_