While dragging a window, show a semi-transparent aura window instead of the standard gray phantom wi

ash/wm/workspace/phantom_window_controller.h

Index: ash/wm/workspace/phantom_window_controller.h
diff --git a/ash/wm/workspace/phantom_window_controller.h b/ash/wm/workspace/phantom_window_controller.h
index 7ea76c41012e6f2089347baa74d8a6cbacacef90..9e7262dd5b236b79058ba8d2a09899c8837a07e6 100644
--- a/ash/wm/workspace/phantom_window_controller.h
+++ b/ash/wm/workspace/phantom_window_controller.h
@@ -9,10 +9,12 @@
 #include "base/basictypes.h"
 #include "base/memory/scoped_ptr.h"
 #include "ui/base/animation/animation_delegate.h"
+#include "ui/gfx/display.h"
 #include "ui/gfx/rect.h"
 
 namespace aura {
 class Window;
+class RootWindow;
 }
 
 namespace ui {
@@ -30,7 +32,14 @@ namespace internal {
 // of a window. It's used used during dragging a window to show a snap location.
 class ASH_EXPORT PhantomWindowController : public ui::AnimationDelegate {
  public:
-  explicit PhantomWindowController(aura::Window* window);
+  enum Style {
+    STYLE_SHADOW,  // for window snapping.
+    STYLE_WINDOW,  // for window dragging.
+  };
+
+  PhantomWindowController(aura::Window* window,
+                          aura::RootWindow* root_window,
+                          Style style);
   virtual ~PhantomWindowController();
 
   // Bounds last passed to Show().
@@ -56,6 +65,14 @@ class ASH_EXPORT PhantomWindowController : public ui::AnimationDelegate {
     phantom_below_window_ = phantom_below_window;
   }
 
+  Style style() const {
+    return style_;
+  }
+
+  // Sets/gets the opacity of the phantom window.
+  void SetOpacity(float opacity);
+  float GetOpacity() const;
+
   // ui::AnimationDelegate overrides:
   virtual void AnimationProgressed(const ui::Animation* animation) OVERRIDE;
 
@@ -63,9 +80,17 @@ class ASH_EXPORT PhantomWindowController : public ui::AnimationDelegate {
   // Creates and shows the |phantom_widget_| at |bounds|.
   void CreatePhantomWidget(const gfx::Rect& bounds);
 
+  // Sets bounds of the phantom window. The window is shown on |dst_display_|
+  // if its id() is valid. Otherwise, a display nearest to |bounds| is chosen.
+  void SetBoundsInternal(const gfx::Rect& bounds);
+
   // Window the phantom is placed beneath.
   aura::Window* window_;
 
+  // The display where the phantom is placed. When dst_display_.id() is -1, a
+  // display nearest to the current |bounds_| is automatically used.
+  gfx::Display dst_display_;
+
   // If set, the phantom window should get stacked below this window.
   aura::Window* phantom_below_window_;
 
@@ -81,6 +106,9 @@ class ASH_EXPORT PhantomWindowController : public ui::AnimationDelegate {
   // Used to transition the bounds.
   scoped_ptr<ui::SlideAnimation> animation_;
 
+  // The style of the phantom window.
+  Style style_;
+
   DISALLOW_COPY_AND_ASSIGN(PhantomWindowController);
 };