Extract the code for supporing extended desktop from WorkspaceWindowResizer into DragWindowResizer.

ash/wm/drag_window_resizer.h

Index: ash/wm/drag_window_resizer.h
diff --git a/ash/wm/drag_window_resizer.h b/ash/wm/drag_window_resizer.h
new file mode 100644
index 0000000000000000000000000000000000000000..198508dc4643bf95e57c3dd287a446622b6ebd65
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+++ b/ash/wm/drag_window_resizer.h
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+// 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_DRAG_WINDOW_RESIZER_H_
+#define ASH_WM_DRAG_WINDOW_RESIZER_H_
+
+#include "ash/wm/window_resizer.h"
+#include "base/compiler_specific.h"
+#include "base/gtest_prod_util.h"
+#include "ui/gfx/point.h"
+
+namespace ash {
+namespace internal {
+
+class DragWindowController;
+
+// DragWindowResizer is a decorator of WindowResizer and adds the ability to
+// drag windows across displays.
+class ASH_EXPORT DragWindowResizer : public WindowResizer {
+ public:
+  explicit DragWindowResizer(WindowResizer* window_resizer,
+                             const Details& details);
+  virtual ~DragWindowResizer();
+
+  // WindowResizer overides:
+  virtual void Drag(const gfx::Point& location, int event_flags) OVERRIDE;
+  virtual void CompleteDrag(int event_flags) OVERRIDE;
+  virtual void RevertDrag() OVERRIDE;
+  virtual aura::Window* GetTarget() OVERRIDE;
+
+  const gfx::Point& GetInitialLocationInParentForTest() const {
+    return details_.initial_location_in_parent;
+  }
+
+ private:
+  FRIEND_TEST_ALL_PREFIXES(DragWindowResizerTest, DragWindowController);
+
+  // Updates the bounds of the phantom window for window dragging. Set true on
+  // |in_original_root| if the pointer is still in |window()->GetRootWindow()|.
+  void UpdateDragWindow(const gfx::Rect& bounds, bool in_original_root);
+
+  // Returns true if we should allow the mouse pointer to warp.
+  bool ShouldAllowMouseWarp();
+
+  scoped_ptr<WindowResizer> window_resizer_;
+
+  // Shows a semi-transparent image of the window being dragged.
+  scoped_ptr<DragWindowController> drag_window_controller_;
+
+  const Details details_;
+
+  gfx::Point last_mouse_location_;
+
+  // If non-NULL the destructor sets this to true. Used to determine if this has
+  // been deleted.
+  bool* destroyed_;
+
+  DISALLOW_COPY_AND_ASSIGN(DragWindowResizer);
+};
+
+}  // namespace internal
+}  // namespace aura
+
+#endif  // ASH_WM_DRAG_WINDOW_RESIZER_H_